Will a tyre pressure light fail an MOT?

It depends entirely on why it is on, and this is the distinction most people get wrong. The MOT fails the car when the monitoring system is malfunctioning or obviously not working — that is a major defect under section 5.2.3 of the inspection manual, and it accounts for 97,515 failures in the DVSA data behind this site, making it the second largest warning-lamp defect of any kind. A lamp that is lit simply because a tyre genuinely needs air is not that defect. An obviously under-inflated tyre is recorded separately and is only a minor defect. The manual is explicit that a tester must only reject the car where it is clear the lamp indicates a system malfunction, and it instructs them to add an advisory instead where they cannot tell. The rule applies to cars first used on or after 1 January 2012.

Why is my tyre pressure light on when all the tyres look fine?

Because a tyre can be a long way down before it looks wrong, and because most systems warn at around a quarter below the recommended pressure, which is not visible. Check all four with a gauge when the tyres are cold. Cold weather alone will do it: pressure falls by roughly one psi for every five or six degrees the temperature drops, which is why so many of these lamps appear on the first frosty morning of the year. Also check the spare if your car monitors it, and remember that on an indirect system the lamp will stay on until you reset it, even after you have corrected the pressures.

How do I reset the tyre pressure warning light?

First correct the pressures, because resetting a system that is reporting a genuinely soft tyre just hides the problem until it gets worse. On an indirect system, which measures nothing and works from a stored baseline, you must then run the reset routine — usually a menu item on the driver's display or a button in the glovebox or under the dashboard — with the car stationary and the pressures correct. On a direct system with sensors in the wheels there is normally nothing to do: the lamp goes out by itself after a few minutes of driving once the sensors report healthy pressures. If it does not, the system has a fault rather than a pressure problem.

Is it safe to drive with the tyre pressure light on?

Only as far as the nearest airline, and gently. An under-inflated tyre flexes more than it should, builds heat, wears out its shoulders, lengthens your braking distance and is markedly worse in the wet. A badly soft tyre can overheat and fail suddenly at motorway speed. If the lamp comes on while you are driving and the car starts pulling, feeling vague or making a rhythmic noise, slow down and stop somewhere safe rather than pressing on, because that is a rapidly deflating tyre rather than a slow loss.

Dashboard warning light

Tyre pressure warning light

Last updated 27 July 2026

Quick answer

At least one tyre has lost enough pressure for the monitoring system to notice, or the system itself has developed a fault. The symbol is a cross-section of a tyre — the shape people describe as a horseshoe or a cupped hand — with an exclamation mark in the middle.

What to do: Get it checked within days
Can you drive?: Briefly, gently

Why it is amber

A system has reported a malfunction, or something needs attention. The car is usually still driveable, but the fault will not clear itself and several amber lamps are an automatic MOT failure.

What turns it on

There are two kinds of system and they behave differently. A direct system has a battery-powered sensor inside each wheel, usually built into the valve, transmitting actual pressure by radio; it typically warns at around a quarter below the recommended pressure. An indirect system has no sensors at all and infers pressure from the ABS wheel speed sensors, because a soft tyre has a smaller rolling radius and therefore turns slightly faster than the others. Indirect systems have to be reset manually after any pressure adjustment, since they work from a stored baseline rather than a measurement.

What to do about it

Check all four tyres with a gauge, not by eye. A radial tyre can be a long way down before it looks wrong, and the difference between a tyre that is slightly soft and one that is dangerously soft is invisible from three feet away.
Inflate to the figure on the placard in the driver's door shut, the fuel filler flap or the handbook — not the number moulded into the tyre sidewall, which is the tyre's maximum rating rather than your car's recommended pressure.
Check them cold, before driving or at least a couple of hours after. Pressures read several psi higher on a hot tyre and you will end up under-inflating.
Look for the cause once they are up. Run your hand round the tread for a nail or a screw, check the valve for perishing, and look at the wheel rim for kerb damage or corrosion where the tyre seals.
Reset the system afterwards if your car needs it. Indirect systems almost always do, usually through a menu or a button; direct systems normally clear themselves after a short drive.
If the lamp returns within days, you have a slow puncture rather than a lazy top-up. Get it looked at before it becomes a deflation at speed.
If the lamp flashed for about a minute at start-up before staying on, this is not a soft tyre — it is a system fault, and it is the version that fails the MOT.

Can you keep driving?

Briefly, gently

Get to somewhere with an airline and check the pressures. An under-inflated tyre overheats, wears its shoulders away, lengthens your braking distance and handles badly in the wet, and a seriously soft one can fail suddenly at motorway speed. If a tyre is visibly flat rather than merely low, do not drive on it at all: running a flat tyre wrecks the sidewall in a very short distance and turns an easy repair into a replacement.

What causes it

A tyre that has genuinely lost pressure through normal seepage, which every tyre does over months
A drop in air temperature, which is why so many of these lamps appear on the first properly cold morning of autumn — pressure falls by roughly one psi for every five or six degrees Celsius
A slow puncture from a nail or screw, often holding air well enough to be missed on a visual check
A perished, corroded or damaged valve, which is a very common failure on the aluminium valve stems used in direct sensors
A kerbed or corroded wheel rim letting air past the bead
A flat or partially inflated spare, on cars whose system monitors it
A dead sensor battery, or a system that has never been reset after a tyre change — the system-fault case rather than the pressure case

Does it fail an MOT?

Yes. A tester records it as a major defect, under the wording A tyre pressure monitoring system malfunctioning or obviously inoperative in the MOT inspection manual (section 5.2.3).

Cars first used on or after 1 January 2012, which is when tyre pressure monitoring became a type-approval requirement. Cars first used before that date are not inspected for it, even if a system happens to be fitted.

It is not a technicality either. Across the DVSA test data behind this site, 97,515 MOTs were failed on it, spread across 342 different models.

Models where it happens most

Share of all tests on that model where this defect was recorded, among models with at least 20,000 tests. Compared against 0.59% across every model that records it.

Vauxhall Viva5.51%
2,104 of 38,153 tests
Vauxhall Mokka2.27%
5,767 of 254,046 tests
Ford Grand C-Max2.25%
778 of 34,572 tests
Jeep Renegade1.90%
555 of 29,154 tests
Hyundai IX351.72%
857 of 49,770 tests
Ford B-Max1.66%
888 of 53,638 tests
MG HS1.12%
365 of 32,716 tests
MG 30.97%
242 of 24,958 tests

A high rate is not proof a model is badly built. Fleet age, annual mileage and how a model is used all move these figures, and vans and commercial derivatives sit near the top of most emissions defects for that reason rather than through poor engineering.

Fault codes that turn this light on

The lamp tells you which system reported a problem. The code stored behind it names the check that failed, which is the difference between knowing something is wrong and knowing where to look. These are the ones that commonly sit behind this symbol.

C0950 Front left tyre pressure sensor not reporting
C0951Tyre Pressure Monitoring Sensor Front Right
C0952Tyre Pressure Monitoring Sensor Rear Left
C0953Tyre Pressure Monitoring Sensor Rear Right
C0900TPMS Sensor 1 Battery

Got a different code? Look it up — the index covers every standard OBD-II code.

Common questions

Will a tyre pressure light fail an MOT?: It depends entirely on why it is on, and this is the distinction most people get wrong. The MOT fails the car when the monitoring system is malfunctioning or obviously not working — that is a major defect under section 5.2.3 of the inspection manual, and it accounts for 97,515 failures in the DVSA data behind this site, making it the second largest warning-lamp defect of any kind. A lamp that is lit simply because a tyre genuinely needs air is not that defect. An obviously under-inflated tyre is recorded separately and is only a minor defect. The manual is explicit that a tester must only reject the car where it is clear the lamp indicates a system malfunction, and it instructs them to add an advisory instead where they cannot tell. The rule applies to cars first used on or after 1 January 2012.
Why is my tyre pressure light on when all the tyres look fine?: Because a tyre can be a long way down before it looks wrong, and because most systems warn at around a quarter below the recommended pressure, which is not visible. Check all four with a gauge when the tyres are cold. Cold weather alone will do it: pressure falls by roughly one psi for every five or six degrees the temperature drops, which is why so many of these lamps appear on the first frosty morning of the year. Also check the spare if your car monitors it, and remember that on an indirect system the lamp will stay on until you reset it, even after you have corrected the pressures.
How do I reset the tyre pressure warning light?: First correct the pressures, because resetting a system that is reporting a genuinely soft tyre just hides the problem until it gets worse. On an indirect system, which measures nothing and works from a stored baseline, you must then run the reset routine — usually a menu item on the driver's display or a button in the glovebox or under the dashboard — with the car stationary and the pressures correct. On a direct system with sensors in the wheels there is normally nothing to do: the lamp goes out by itself after a few minutes of driving once the sensors report healthy pressures. If it does not, the system has a fault rather than a pressure problem.
Is it safe to drive with the tyre pressure light on?: Only as far as the nearest airline, and gently. An under-inflated tyre flexes more than it should, builds heat, wears out its shoulders, lengthens your braking distance and is markedly worse in the wet. A badly soft tyre can overheat and fail suddenly at motorway speed. If the lamp comes on while you are driving and the car starts pulling, feeling vague or making a rhythmic noise, slow down and stop somewhere safe rather than pressing on, because that is a rapidly deflating tyre rather than a slow loss.

This is general guidance, not a diagnosis. Manufacturers draw the same system differently and reuse symbols for more than one function, so check the handbook for your own car before acting on anything here.

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