Consumer-level vehicle maintenance, consumables and warning indicators.
This is a dated snapshot.
Check the current live page and the documentation supplied with your equipment
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29 published pages.
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Check an automatic transmission fluid level, or establish that the transmission is sealed and has no dipstickChecking automatic transmission fluid is not one job: it is two different outcomes depending on the vehicle. Many automatics have a dipstick the owner can read, usually with strict conditions attached — a stated gear position, sometimes the engine running rather than off, sometimes a fluid temperature reached only after several minutes of driving. A growing number of modern transmissions have no dipstick at all: Toyota's own guidance says most newer vehicles use a sealed transmission system whose internal mechanisms manage the fluid level, and the correct response to a suspected problem is a technician's check, not an owner's check.
This page will not print a single set of conditions, a single fluid type, or a single mark to fill to, because none of those is true of every vehicle — Kia's own manual, for one real example, calls for the engine running at idle in Neutral, the fluid warmed to a stated range, and the gear selector cycled through every position before the reading is taken, none of which a generic page could safely guess for a different make. What it will do is show you what to look for, what a normal colour looks like against a concerning one, and exactly when to stop and call a professional instead of guessing.Version 1 · updated 2026-08-04
Check headlight aim against a wall and find the adjustersEvery vehicle's headlights must aim within federal tolerances to ensure visibility and prevent glare for oncoming drivers. The wall method checks aim using masking tape marks at a measured distance from the vehicle. This procedure teaches the test method and how to locate the adjusters; the exact wall distance, beam-cutoff tolerance, and number of turns required for your vehicle are in your owner's manual or from a licensed inspection station.Version 2 · updated 2026-08-03
Choose and change windscreen washer fluid before freezing weatherSummer washer fluid is mostly water, and water freezes. When it freezes inside the reservoir, the pump or the lines, a two-dollar bottle of the wrong fluid can turn into a cracked reservoir or a dead pump right when you need clear glass the most. The fix costs almost nothing: check the freeze-point rating printed on the bottle before you buy, and choose one rated at or below the coldest temperature you expect.
This page covers choosing a fluid, checking and topping up the reservoir, and testing the washer afterward — ordinary maintenance most drivers can do in the driveway. It will not print a single freeze-point number for you to buy, because every product's rating is different and the only reliable place to read it is the label on the bottle in your hand. It also covers two mistakes that are easy to make without realizing the risk: adding plain water once the weather turns cold, and reaching for engine coolant because the color looks similar. Two vehicle manufacturers whose manuals this page draws on both warn against the second one directly.Version 2 · updated 2026-08-04
Find the date code on a vehicle battery and work out how old it actually isNobody looks up a car battery's age for fun. The question comes up when the battery is slow to start the engine, when a shop is checking whether it is still under warranty, or when someone buying a used car wants to know what they are getting. The trouble is that the label on the case usually carries more than one code, and only one kind of code is a date. A group size code tells a parts store which battery fits the tray, not when it was made. A cold cranking amps rating tells you how much starting power the battery delivers, not its age. Only a code your battery maker specifically names as a date code tells you when the battery was made.
This page will not hand you a decode table for every brand on the market, because most battery makers keep their date code scheme private. East Penn Manufacturing, which makes Deka-brand batteries and batteries sold under other names, publishes its own scheme on its own site: a two-part code with the month before a slash and the two-digit year after it, so 3/23 reads as March of 2023. If your battery is not a Deka, or you cannot confirm East Penn made it, the honest next step is the battery maker's own website or a phone call, not a chart from a site that is not the manufacturer. This page also shows the two codes most often mistaken for a date - the group size code and East Penn's own production code - so a wrong guess does not become a wrong age.Version 1 · updated 2026-08-04
How do I check that my lug nuts (wheel nuts) are still tight after a tire shop, a mobile fitter, or a roadside wheel change?A tire shop, a mobile fitter, or your own roadside wheel change tightens the wheel nuts with a torque wrench, but nearly every vehicle maker still asks you to come back after a short drive and check that wheel again. This page is that re-check: using your own torque wrench to confirm every wheel nut a fitter touched is still at the value your vehicle calls for. People search for this after hearing a clicking or ticking noise a day or two after new tires, after a roadside spare change, or simply because the paperwork from the shop told them to.
This page gives the method only. It does not print a torque number, because that figure is set per vehicle by its own manufacturer and differs by more than a factor of two across the consumer range. It also does not print one universal distance for the re-check: manufacturers' own documentation disagrees on this, and the page names that disagreement rather than picking a side. Get both figures — the torque value and the re-check distance — from your own vehicle's documentation or from the paperwork the fitter gave you.Version 1 · updated 2026-08-04
How to change a headlight bulbOne headlight out is one of the few car faults you can often fix on your own driveway for the price of a bulb, and one of the few where the wrong part is genuinely dangerous rather than merely annoying. On a lot of cars the job is a twist, a pull and a click: reach behind the headlamp, release the connector, turn the retainer, and the old bulb comes out. On plenty of other cars it is not that at all, and the first useful thing this page does is help you find out which car you have before you buy anything.
What this page will not do is tell you which bulb your car takes. There is no single answer: the bulb type is per-vehicle, your owner's manual is the authority for yours, and there is a second copy of the answer in the car already, because federal rules require a replaceable headlight bulb to carry its own marking designation. So the page teaches you to read the answer off your own vehicle rather than printing a number that would be wrong for most readers. It stops, hard, at three headlamp types: high-intensity discharge (HID or xenon), integrated LED units, and sealed beam. It also will not tell you to fit LED bulbs into a halogen headlight, because NHTSA's Acting Chief Counsel has said in writing that no LED replaceable light source may be used in a replaceable bulb headlamp. And it does not touch headlight aim, which is a separate job with its own measurements.Version 1 · updated 2026-07-29
How to change the battery in a car key fobA key fob that only works when you are standing next to the car is usually a flat coin cell rather than a broken remote. Mazda's owner's manual lists a reduced operational range as one of the three signs that the key battery is low, alongside a flashing KEY indicator and a transmitter light that no longer blinks. Changing the cell is a five-minute job on a kitchen table. The two things that go wrong are buying the wrong cell and putting it in upside down, and both are avoidable if you read the old cell before you throw it away.
This page will not tell you which cell your fob takes, and that is deliberate. Mazda's 2018 CX-5 manual says CR2025 and Mazda's 2025 CX-30 manual says CR2032 — one manufacturer, two answers, because it depends on the fob. Kia's smart key page says CR2032, and Kia's Seltos manual describes the cell as a 3 volt lithium battery. So the page hands you the two places the right answer actually lives: the marking stamped on the cell you are taking out, and the key section of your own vehicle's documentation. It also takes the swallowing hazard seriously, because a lithium coin cell is the one part of this job that can kill a small child, and both Kia's manual and the US Consumer Product Safety Commission say so in those terms.Version 4 · updated 2026-08-04
How to change the cabin air filter in a car when the air conditioning smells or barely blowsA cabin air filter is the one that cleans the air coming into the car, and it is not the engine air filter. When it clogs, the first symptom is usually weak airflow from the vents with the blower on full, and the second is a musty smell. Toyota lists a clogged or extremely dirty cabin air filter as a common cause of no airflow from the car's air conditioning, and Mazda says the same thing from the other direction: if airflow drops significantly, the filter may be clogged. It is a fifteen-minute job on most cars and a dealer job on a few.
This page teaches you to find the housing rather than telling you where it is, because the location is genuinely model-specific — behind the glove box on many cars, under the scuttle or under the dash on others. It also will not print a part number or an airflow direction for your car. The direction matters: a cabin filter has an arrow printed on its frame, the arrow has to end up pointing the same way the old one did, and fitted backwards the filter can collapse and choke the very airflow you were trying to fix. The old filter in your hand is the authority for both, which is why this page has you read it before you throw it away.Version 1 · updated 2026-07-29
How to change the engine air filter in your carThe engine air filter is a paper or fabric panel in a plastic box near the top of the engine, and on most cars it is held in by clips or a few screws. Swapping it is one of the few jobs on a car that needs no tools you do not already own, no lifting equipment, and no part of you underneath the vehicle. The work that matters is not the swapping. It is getting the right part, putting it in the same way round as the one you took out, and closing the box so that the seal is actually made.
What this page will not print is the part number for your car, the replacement interval for your car, or a torque for the cover fasteners. Those are per-vehicle and the only reliable places to get them are your own maintenance schedule and the frame of the filter you remove. There is also a live disagreement between manufacturers about whether a used element may be blown out with compressed air and refitted: Hyundai and Kia allow it, Nissan tells you the element should not be cleaned and reused. This page publishes both instructions and does not pick one for you.Version 1 · updated 2026-07-29
How to change your windshield wiper bladesWorn wiper blades are one of the cheapest problems on a car to fix and one of the easiest to put off until it is already raining. On most vehicles the job needs no tools at all: the old blade unclips from the arm and the new one clicks on. This page covers the whole thing — parking somewhere safe, working out which blade and which connector your car takes, getting the old blade off without letting the arm drop onto the glass, and testing the wipe before you drive.
What this page will not do is print a blade size or a connector type for your car, because there are thousands of combinations and the authority for yours is your owner's manual or the blade maker's vehicle guide. It also will not tell you how to raise your wiper arm, and that is deliberate: Mazda says to move the wipers to a service position first, Tesla puts that mode behind a touchscreen menu, and Toyota warns that lifting an arm parked under the hood can damage the hood. The replacement interval is the one thing the manufacturers here agree on. Toyota gives six to 12 months and Tesla says at least once a year, so this page publishes six to 12 months and names where it came from.Version 1 · updated 2026-07-29
How to check if your spare tire is there, in good shape and has enough airA flat tire is discovered at the worst possible moment, and that is exactly when most drivers learn their spare has a problem too. This check finds a bad spare while the car is still on the driveway: is the wheel actually there, is the tire free of damage, and does it hold the pressure it needs. It needs no lifting equipment and takes about fifteen minutes. Federal regulation requires the vehicle placard to carry a recommended cold inflation pressure for the spare tire, the same placard that carries the figure for the road tires.
Two things surprise most drivers. A temporary spare tire needs far more air than a road tire, and its own label and the vehicle placard both say so. Many newer vehicles carry no wheel at all: a tire sealant kit with its own expiry date takes its place, and that kit has its own page on this site. What this page will not print is a single pressure value or a single speed limit for every car — those are per-vehicle figures, printed on the placard and on the tire itself, and a page that guessed one would be guessing with the number that decides whether the tire holds.Version 1 · updated 2026-08-04
How to check the tire sealant and inflator kit your car carries instead of a spare tireMost new cars no longer carry a spare wheel. In its place there is a small case in the trunk holding a bottle of tire sealant and a little electric compressor, and almost nobody opens it until the moment a tire goes down. That is the wrong moment, because the sealant in that bottle has an expiry date on the label and will be refused by its own manufacturer once the date passes. Mazda asks owners to inspect the kit at regular intervals, to check the sealant's period of effective use and to check that the compressor still runs; Honda lists expired sealant first among the situations in which the kit must not be used and the car must be towed instead. This page is that inspection, done on your own driveway, in about ten minutes.
What this page will not print is the expiry date, the biggest puncture your kit will seal, the speed limit after a repair, or how long your compressor may run. Those are properties of your kit and your car, they are printed on the kit itself and in your owner documentation, and a page that guessed them would be guessing with the numbers that decide whether the repair works. What this page does instead is teach you where each of them is written, and give you somewhere to write them down while you are calm and the car is on the driveway. One thing worth knowing before you buy a replacement bottle anywhere other than the dealer: General Motors states in its own service bulletin that tire pressure sensors are not compatible with commercially available tire sealants, and that sealant can clog the sensor's pressure port.Version 1 · updated 2026-07-29
How to check tire tread depth and know when you need new tiresEvery tire sold in the United States carries its own wear gauge, moulded into the tread. Federal Motor Vehicle Safety Standard No. 139 requires at least six treadwear indicators — almost everyone calls them wear bars — spaced around the tire, and they become level with the tread surface when the tread has worn to one sixteenth of an inch. NHTSA writes the same depth in the other unit and says a tire is not safe and should be replaced when the tread is worn down to 2/32 of an inch. This page shows you where the bars are, three ways to read the depth, and what an uneven wear pattern is telling you.
It does not print a legal minimum for your car. The federal figures that do exist — 4/32 of an inch on the front wheels of a bus, truck or truck tractor, and 2/32 of an inch elsewhere — belong to the FMCSA rule for commercial vehicles in interstate commerce, not to a private car, and for a private car the minimum is state law and it varies. It also does not print an early-replacement depth for wet weather, because no primary source publishes one for passenger cars and a number invented to fill the gap would be worse than the gap. Your vehicle documentation and your tire manufacturer are the authority for your own tires, and this page tells you what to measure before you ask them.Version 1 · updated 2026-07-29
How to check your coolant level without opening the radiator capChecking the coolant is a look, not a job with tools. Most vehicles have a plastic reservoir under the hood with a wall you can see through and two marks printed on it, and on a cold engine you can read the level through that wall without touching a cap. This page walks through finding the reservoir, reading the marks, and knowing what a low reading means. It does not walk through opening anything.
What this page will not do is tell you which coolant to add. Coolant chemistry is not one universal fluid — Mazda's own manual warns that a coolant other than the one it specifies 'may cause serious damage to the engine and cooling system,' and Ford's manual carries the same warning about mixing colours or types. Add coolant only after you check your own vehicle documentation. And if the level keeps returning to low, this page will not talk you through finding the leak: a level that drops again soon after you check it is a job for a repair shop, not a habit of adding more fluid.Version 1 · updated 2026-08-04
How to check your engine oil and work out what oil your car takesChecking the oil is two jobs that people run together. The first is a measurement: is there enough oil in the engine right now. The second is a specification question: which oil does this engine take when you need to add some. This page keeps them apart, because the measurement is the same on almost every car with a dipstick and the specification is different on almost every car — sometimes different between two engines in the same model, in the same year.
What this page will not print is a viscosity grade, an oil standard or a capacity for your engine. Those come from your own vehicle documentation and from the label on the oil filler cap, and a page that guessed one would be guessing with the thing that actually damages an engine. There is one more honest wrinkle. Manufacturers do not agree on the state the engine should be in when you read the dipstick: Mazda asks you to warm the engine, stop it and wait at least five minutes, while Subaru simply asks you to park level, switch off and wait a few minutes. Both are on this page, neither is averaged, and your own manual is the tie-breaker.Version 1 · updated 2026-07-29
How to check your tire pressure and put the right amount of air in your tiresTire pressure is the cheapest safety check on a car and the one people most often get wrong, because the big number moulded into the side of the tire is not the number you are supposed to use. NHTSA puts it plainly: the correct pressure for your tire is what the vehicle manufacturer has listed, not what is listed on the tire itself. That figure lives on the Tire and Loading Information placard, usually on the driver's door edge or the pillar behind it, and federal regulation is what puts it there. This page covers the whole check — finding the placard, measuring while the tires are cold, adding or letting out air, and doing the spare, which almost nobody does.
What this page will not print is a psi number for your car, and that is the point rather than a gap. Every vehicle has its own placard figure, and a page that guessed one would be guessing with the only number that matters. Three things here the gauge alone will not tell you. NHTSA asks for a check at least once a month with the tires cold, and Mazda's owner's manual gives the same three-hour parked rule for a cold reading. The dashboard warning light is not an early warning either: FMVSS No. 138 lets it stay dark until a tire is 25 percent below the placard figure, which is a long way down.Version 1 · updated 2026-07-29
How to find and replace a blown fuse in your carWhen one thing in a car stops working and everything else is fine — the cigarette lighter socket, the radio, one interior lamp — the cheapest explanation is a single blown fuse, and it is a part that costs less than a coffee. The job itself is genuinely easy: open the right fuse box, pull the right fuse with the little plastic puller the manufacturer already put in the car, look at the metal strip inside it, and push in a new one. What makes it go wrong is not the manual work. It is putting back the wrong fuse.
This page publishes the method and deliberately publishes no numbers. Every amperage rating, every fuse position and the location of the fuse panels themselves are specific to your vehicle, and they are printed on the fuse box lid and in your own owner's manual — so the page teaches you to read them there rather than guessing them here. The one rule that generalises is the one that matters: a replacement fuse must carry the same amperage rating as the fuse it replaces, because a bigger fuse does not fix anything, it just moves the weakest point from a part you can replace to the wires you cannot. The page also stops where the manufacturers stop. Bolted, main and high-current fuses are a dealer job, and a fuse that blows a second time is a fault, not a fuse.Version 1 · updated 2026-07-29
How to find your car's maintenance schedule and record what maintenance is actually dueEvery vehicle comes with a maintenance schedule, and that schedule is really two schedules: a normal one, and a severe (or "special conditions") one for drivers who make a lot of short trips, drive a lot of stop-and-go city traffic, tow a trailer, or drive in extreme heat or cold. Most people who meet those conditions have never heard the term "severe service" and default to the normal schedule without ever checking which one is meant for them. This page shows you how to find your own vehicle's schedule, read the manufacturer's own definition of severe conditions to work out which schedule actually applies to how you drive, and write the answer down against today's odometer reading and date so you can see, at a glance, what maintenance is genuinely due.
What this page will not do is print a mileage figure or a time interval, because both are specific to the vehicle: the make, the model, the model year, and sometimes the engine and the trim. Toyota's own guidance is blunt about it: "your owner's manual will tell you when your recommended services should happen." Ford's support site makes the same point from the other side: "for more information about recommended maintenance, refer to your Owner's Manual under Scheduled Maintenance." So this page carries the method and the record format only. The numbers come from your own vehicle's manual.Version 1 · updated 2026-08-04
How to read a tire sidewall and find out how old your tires areEvery tire carries its own date of manufacture, its size and its limits, moulded into the sidewall. The code that gives the age is the DOT Tire Identification Number, and the last four digits are the week and the year the tire was made. Federal regulation sets that format, so it reads the same way on every tire sold in the United States. This page shows you where to look and how to read what you find.
It does not tell you when to replace a tire, and it does not print a pressure. NHTSA says the correct inflation pressure is the one the vehicle manufacturer lists on the placard, not the maximum number moulded into the sidewall. Replacement age is a manufacturer question too, and vehicle makers and tire makers do not give the same answer. Both are marked here as consult-the-manufacturer on purpose.Version 1 · updated 2026-07-29
How to read the check engine light codes on your car with a cheap code readerEvery car sold in the United States since model year 1996 carries a self-diagnostic system that watches the emission control equipment, stores a trouble code when something fails, and turns on the check engine light to tell you it did. A twenty-dollar reader will pull those codes out through a standard connector, and this page is about doing that properly. It is deliberately not about deciding what the code means — EPA's own inspection rules say that proper diagnosis by a qualified technician is required to positively identify the source of an emission-related problem, and that is the honest boundary for a page like this one.
So the aim here is to end up with a written record: the codes, the freeze frame data captured when the fault was detected, and the status of the readiness monitors. Two things matter more than everything else on this page. A check engine light that flashes is not the same as one that stays on, and a flashing one means stop rather than carry on. And clearing a code does not fix anything — it also wipes the readiness monitors, and a car with unset monitors is failed at an emissions inspection under 40 CFR 85.2222. Read, record, hand over. Do not clear.Version 1 · updated 2026-07-29
How to read the tire and loading information placard and work out how much load you have left for passengers and cargoYour vehicle's Tire and Loading Information placard carries more than a tire pressure number. Federal regulation 49 CFR 571.110 also requires two figures about weight: how many people the vehicle is designed to seat, and a line that reads something like ‘The combined weight of occupants and cargo should never exceed XXX kg or XXX lbs.’ That second figure is the one that matters on a trip with a full car, luggage, and maybe a roof box. It sets the ceiling for everyone and everything you put in the vehicle, and it is easy to miss because it shares a label with the tire pressure numbers most drivers already check.
This page will not print a weight limit for your vehicle, because that figure is set per vehicle and per trim by the manufacturer, and a guessed number here is exactly the kind of value this site refuses to publish. Instead it walks through the arithmetic with your own numbers: read the placard figure, total the actual weight of the driver and passengers, subtract that from the placard figure, and what is left is your available capacity for cargo and luggage. Owner's manuals from more than one manufacturer describe this same method, and this page follows it rather than inventing a shortcut. If you tow a trailer, the trailer adds its own weight to the calculation, and the page covers that too.Version 1 · updated 2026-08-04
How to reset the service light, oil change light or maintenance required light on a car after an oil changeMost cars, trucks and SUVs carry a maintenance reminder — a wrench symbol, or a message such as Maintenance Required, Service Due, or Oil Life — that turns on once a preset mileage or a preset number of days has passed. Once the service is actually done, the reminder does not clear itself. An owner or a shop has to reset it, and the method is different for nearly every manufacturer and often for every model year. Some vehicles clear it with a button held through an ignition cycle, some from a menu on the instrument display, and some with the accelerator pedal pressed a set number of times. On a few vehicles, the manufacturer's own documentation asks for a repair shop to do it.
This page will not give a single button sequence that works on every vehicle, because none exists: a sequence correct for one manufacturer can do nothing at all on another. What generalizes across every vehicle is one distinction that matters more than any button press: this reminder is a counter, not a fault check, and it is not the malfunction indicator lamp, commonly called the check engine light. Resetting the counter changes nothing mechanical and does not clear or examine the check engine light. Read the vehicle documentation for the exact sequence for this vehicle, and confirm the reset worked before you consider the job finished.Version 1 · updated 2026-08-04
How to test a car battery with a multimeterA multimeter across the two terminals of a car battery gives you one number, the open circuit voltage, and that number is the cheapest early warning of a battery going flat on you. It is also the number the internet is most confident and least careful about. Almost every page you will find says 12.6 volts means fully charged. That is East Penn's figure for a flooded battery, and it is not what Odyssey or Optima say about theirs — on Odyssey's own AGM2 table, 12.6 volts is 75 percent charged, not 100. This page shows you how to take the reading without hurting yourself, and then hands you to the manufacturer of the battery you actually own.
The hazards are real and they come from the battery, not the meter. Every lead-acid battery makes explosive hydrogen gas, and every one of them contains sulfuric acid that will burn skin and destroy clothing — East Penn's own document says both in capital letters, and OSHA's battery standard exists for the same reason. Eye protection goes on before you open the hood, not after. This page also stops where honest DIY stops: a voltage reading does not prove a battery can still start an engine. That is a load test, it needs equipment you probably do not have, and East Penn says plainly that it is the best way to find out.Version 1 · updated 2026-07-29
Read the treadwear, traction and temperature grades moulded on a tire and know what they do and do not compareMost passenger car tires sold in the United States carry three federal grades moulded into the sidewall: a TREADWEAR number, a TRACTION letter and a TEMPERATURE letter. Together they make up the Uniform Tire Quality Grading System, or UTQG, created by 49 CFR 575.104. This page shows exactly where to find each grade and what each one measures, using the wording of the regulation itself and NHTSA's own consumer material.
It will not tell you which grade to buy, and it will not tell you that a number on one brand of tire means the same thing as the same number on a different brand. Under the regulation, it is each tire's own manufacturer or brand name owner that tests the tire and assigns its grades; NHTSA sets the test procedure and can audit the result, but does not grade every tire itself before it reaches a shelf. None of the government sources this page cites states that a grade from one manufacturer reads straight across against a grade from another manufacturer, so this page does not make that claim either.Version 2 · updated 2026-08-04
What battery does my car take, and how do I read the group size and CCA rating before I buy a replacementA replacement car battery has to match the vehicle in five separate ways at once, and the sticker on the case spells out most of them plainly once you know where to look. The case has to be the right group size so it fits the tray and its cables reach the posts. The positive and negative posts have to sit on the correct sides, and the hold-down bracket has to match the mounting hardware. The cold cranking amps rating has to meet or beat what the vehicle maker specifies. The chemistry — flooded, enhanced flooded, or absorbed glass mat — has to be the one the vehicle's charging system was designed around, which matters more than it used to now that many newer vehicles require AGM.
This page shows you how to read every one of those markings off the battery that is already in the vehicle, and how to check them against the owner's manual before you go shopping, so the battery you bring home is the right one the first time. It does not cover disconnecting the old battery or fitting the new one — those are separate jobs with their own hazards. If a reading is missing or does not match the manual, the safest step is to ask the vehicle maker or a parts store rather than guess.Version 1 · updated 2026-08-03
What does the oil pressure warning light mean, and is it the same as the low oil light?A dashboard light shaped like an oil can, or carrying the words oil or engine oil, is not the same thing as a low oil level, a check engine light, or a wrench-shaped maintenance reminder. It reports one thing only: the pressure of the oil moving through the engine right now, measured by a sensor on the engine block. It says nothing about how much oil is sitting in the pan, which is what a dipstick measures, and a full dipstick does not rule out a pressure problem.
This page tells you how to recognize the oil pressure warning lamp, sets it apart from the wrench-shaped maintenance reminder, and gives the order that keeps a bad five minutes from becoming a replaced engine: stop, stop the engine, wait, check, and only then decide. It will not walk you through reading a dipstick — this site's page on checking the engine oil level covers that — and it will not diagnose why the pressure is low, because that takes a technician with a pressure gauge, not a web page.Version 1 · updated 2026-08-04
What the red brake light on my dashboard means and whether I can keep drivingA red lamp with the word BRAKE in it is not one warning. FMVSS 135, the federal standard for light vehicle brake systems, lets a single lamp stand for any of seven separate conditions: a gross loss of brake fluid or brake system pressure, an electrical failure in the antilock or proportioning system, an applied parking brake, worn-out brake linings, a loss of electrical power on a vehicle with electrically actuated brakes, a failed brake control circuit, or a failed regenerative braking system on an electric vehicle. The standard requires the lamp to be red, requires it to come on for every one of those, and does not require it to tell you which one it found. One of the seven is something you can settle yourself in about a minute. The other six are not.
The second thing worth knowing is that the pattern of this lamp carries no information at all. On the tire pressure lamp a flash means one thing and a steady light means another, and on the check engine lamp that same difference decides whether you keep driving. Here it decides nothing: FMVSS 135 S5.5.4 and FMVSS 105 S5.3.4 both let the manufacturer choose a continuous or a flashing indication for the same condition. What this page does is separate the red lamp from the yellow ABS lamp, rule out the parking brake, and tell you exactly what to write down before you telephone anybody. What it does not do is give you a repair, because work inside a hydraulic brake system is on this site's exclusion list and the boundary is the point of the page.Version 1 · updated 2026-07-29
What the tire pressure light on my dashboard means and what to do about itOne dashboard symbol is asked to say two completely different things, and almost nobody is told which is which. A lamp that comes on and stays on means at least one tire is significantly under-inflated. A lamp that flashes for about a minute and then stays on means the monitoring system itself has failed, and the vehicle can no longer tell you anything about your tires at all. FMVSS No. 138 is the federal standard that defines both behaviours, so they read the same way on every passenger car and light truck sold in the United States since model year 2008. This page shows you how to tell the two apart and what each one asks of you.
What this page will not print is a pressure for your car. That number lives on the Tire and Loading Information placard on your own vehicle, it is different from the maximum number moulded into the tire sidewall, and guessing it would be guessing with the only figure that matters. Two more things worth knowing before you trust the lamp. FMVSS No. 138 lets the lamp stay dark until a tire is a quarter below the placard figure, and gives the system up to twenty minutes to notice. A dark dashboard is therefore not the same as a correctly inflated tire, which is why NHTSA still asks for a check with a gauge once a month.Version 1 · updated 2026-07-29
Work out why a battery is flat every morning when the battery itself tests goodA battery that reads a normal voltage on a multimeter and is still flat the next morning usually has one of two explanations. Either something is drawing power that should not be, in a way you can see and stop for free, or the vehicle draws a small constant current with the ignition off and that current is higher than it should be. This page starts with the free half: a dome light, a door not fully shut, a glove box light, a phone charger left in the socket, and a pattern of short trips that never lets the alternator finish a full charge. Only after those are ruled out does the page move to a current measurement.
The measurement half needs a multimeter, a wait for the vehicle's own computers to go to sleep, and a number to compare against — and that number is the part this page will not guess. A vehicle with two onboard computers and a vehicle with forty do not share one acceptable current, and the wait time before an accurate reading is just as specific to the vehicle. This page shows you how to take the measurement and how to narrow it to one fuse. It sends you to your vehicle's own manufacturer documentation for the two numbers that decide whether what you measured is normal.Version 1 · updated 2026-08-04