Car jargon, decoded

What each light means, and whether it's a stop-now or a get-it-looked-at.

• What does the engine management light mean?It means the engine management system has spotted something wrong - not what the problem actually is.
• What does the tyre pressure warning light mean?One or more tyres is significantly under-pressure - it usually won't tell you which one.
• What does the oil pressure warning light mean?One of the more serious lights - it means the engine may not be getting properly lubricated.
• What does the battery warning light mean?The charging system (usually the alternator) isn't topping the battery up - the car is running on borrowed time.
• What does the brake warning light mean?Usually just the handbrake, but it can also mean low brake fluid or a genuine fault - worth checking which.
• What does the DPF warning light mean?The diesel particulate filter is clogging with soot - short journeys are the usual cause.
• What does the airbag warning light mean?A genuine safety-critical fault: the airbags may not deploy correctly in a crash while this is on.
• What does the coolant temperature warning light mean?The engine is overheating - continuing to drive risks serious, expensive damage.
• What does the ABS warning light mean?Normal braking still works, but you lose the anti-lock function that stops wheels skidding.
• What's the difference between a red, amber and green warning light?Red generally means stop and check now, amber means get it looked at soon, and green or blue is just information.

Plate ages, letters, Q plates, and what a private plate can and can't hide.

• What year is a 74 plate?A 74 plate means the car was first registered between September 2024 and February 2025.
• What year is a 76 plate?A 76 plate means the car was first registered between September 2026 and February 2027.
• How do I tell what year a car is from its number plate?Look at the two digits after the letters - that's the age identifier, issued twice a year since 2001.
• What do the letters on a UK number plate mean?The first two letters point to where the car was first registered, not who owns it or where it lives now.
• What is a Q plate?Issued when a car's true age or identity can't be verified - not automatically a red flag, but worth extra questions.
• Does a private number plate hide a car's age?It hides the age identifier from view, but the car's real first registration date is still on record.
• Is a plate change on a car a bad sign?Not on its own - a plate change is usually just a private plate being added or removed.

The abbreviations that turn up on an MOT history or in a used-car advert.

• What does PRS mean on an MOT?It means the car failed initially but the fault was fixed on the spot within an hour, then passed.
• What does FSH mean?Full Service History - every scheduled service has been done and recorded.
• What's the difference between FSH and FMDSH?FMDSH means every service was done at a manufacturer's main dealer - FSH just means it was serviced somewhere.
• What does OVNO mean?Or Very Near Offer - the seller wants close to the asking price, with only a little room to negotiate.
• What does ONO mean?Or Nearest Offer - similar to OVNO, but generally read as leaving a bit more room to negotiate.
• What is Cat S?The car has had structural damage but has been assessed as repairable and roadworthy again.
• What is Cat N?The car has been written off for non-structural damage - repairable, without the structural questions Cat S carries.
• What's the difference between Cat S, Cat N, Cat C and Cat D?Cat C and Cat D were retired in 2017 and replaced by Cat S and Cat N - many older cars still carry the old labels.
• What is a V5C?The car's official registration document, sometimes called the logbook.
• What does SORN mean?SORN stands for Statutory Off Road Notification - how you officially declare a car is off the public road.
• Is an advisory the same as a fault?No - an advisory means something will likely need attention soon, not that it's already wrong.
• What does "sold as seen" actually mean?It carries real weight in a private sale, but a trader can't use it to remove your statutory rights.
• What is ADAS?Advanced Driver Assistance Systems - the tech that helps with driving, like lane-keep assist and automatic braking.
• What is a vehicle history check?A check of a used car's records for things you can't see by looking at it, like outstanding finance, theft reports and insurance write-offs.
• What is a third party risk marker?A note on a car's history record that an outside organisation has registered an interest in it, for a reason outside the usual finance, stolen and write-off checks.
• What is a salvage auction record?A record that a car was listed at a salvage auction, where damaged and written-off vehicles are usually sold.
• Does the number of previous keepers matter?On its own, not much. It's most useful read alongside the car's service history and MOT record.
• What does a colour change on a car's record mean?The colour registered for the car has been updated, usually after a respray. It isn't a warning sign on its own.

Is it serious? What typically fails, and what's usually just worth keeping an eye on.

• Does a cracked windscreen fail an MOT?It depends on the size and where it is - the closer to the driver's eyeline, the smaller the damage needs to be to fail.
• Is a "corrosion" advisory serious?Usually not urgent yet, but corrosion near a mounting point is worth acting on before it becomes a fail.
• What does "play in steering rack" mean on an MOT?There's more free movement in the steering than there should be before the wheels actually respond.
• Does a warning light on the dashboard fail an MOT?Some do, some don't - it depends which light, and whether it's showing an actual system fault.
• What are the most common MOT failures?Lighting and signalling issues, like blown bulbs, are consistently the single biggest cause, year after year.
• What does "nearside" and "offside" mean?Nearside is the kerb side, offside is the middle-of-the-road side - in the UK, that's left and right.
• Does an engine management light fail an MOT?Usually, if it's on when it shouldn't be - it's checked as part of the MOT's emissions test.
• What tyre tread depth fails an MOT?Below 1.6mm across the central three-quarters of the tyre, anywhere around its circumference.

The components mechanics and adverts mention, in plain English.

• What is a DPF?A Diesel Particulate Filter - it traps soot from the exhaust, and needs regular fast driving to clear itself.
• What's the difference between a timing belt and a timing chain?Both keep the engine's timing in sync - a belt needs replacing on a schedule, a chain usually doesn't.
• What is a catalytic converter?The exhaust part that turns harmful gases into less harmful ones - and a common theft target because of what's inside it.
• What is a clutch and how do I know if it's worn?It connects the engine to the gearbox - slipping, a high biting point or a burning smell usually means it's on its way out.
• What's the difference between brake discs and brake pads?Pads are the friction material that clamps on to slow the car - discs are what they clamp onto, and wear more slowly.
• What is a turbo?A turbocharger uses exhaust gas to force more air into the engine, giving a smaller engine more power.

The practical stuff every owner ends up needing to look up.

• How do I find my tyre size?It's printed on the tyre's sidewall, as a code like 205/55 R16.
• How do I find my tyre pressures?Check the sticker on the driver's door pillar, inside the fuel flap, or the handbook - never guess a figure.
• How do I tell how old a tyre is?Look for the 4-digit date code on the sidewall - it shows the week and year the tyre was made.
• How do I find out what fuel my car takes?Check inside the fuel flap, the V5C, or the handbook - all three normally state petrol or diesel.
• Which side is my fuel cap on?Check your fuel gauge - most cars show a small arrow next to the pump icon pointing to the correct side.
• How do I check my oil level?Most cars: dipstick out, wipe it, back in, out again, and read between the min and max marks.
• Where is the VIN on a car?Commonly visible through the windscreen, inside the driver's door pillar, or under the bonnet - and on the V5C.
• What do I do if I've lost my car keys?Get a replacement from a dealer or locksmith, and think about whether the lost key is a security risk worth acting on.

PCP, HP, excess and the other terms that turn up on a finance agreement.

• What does PCP mean?Personal Contract Purchase - lower monthly payments, but a large final payment if you want to actually own the car.
• What's the difference between PCP and HP?HP pays off the whole car with no final payment - PCP has lower monthly payments but a balloon payment if you want to keep it.
• What is a balloon payment?The large optional payment at the end of a PCP deal - pay it to own the car, or hand the car back instead.
• What is an insurance excess?What you pay towards a claim yourself before your insurer covers the rest.
• What is a no-claims bonus?A discount for each claim-free year - and even a non-fault claim can sometimes still affect it.
• What is GAP insurance?Guaranteed Asset Protection - covers the shortfall between what your car's insured for and what you still owe or paid.

What to do, and who to go to, if a used car goes wrong.

• What are my rights if a used car goes wrong?It depends heavily on whether you bought from a dealer or a private seller - dealers carry far more legal obligation.
• Can I return a used car to a dealer?Within 30 days, generally yes if it's faulty - but changing your mind isn't the same as it being faulty.
• Who do I complain to about a car dealer?Start with Citizens Advice, who can refer serious cases on to Trading Standards.
• What is the Motor Ombudsman?An independent dispute resolution service for the motor industry - but only for businesses signed up to its code.
• What can I do if I bought a car with outstanding finance?UK law gives some protection to private buyers who didn't know about the finance, but whether it applies depends on the details.