Key takeaways
- A solid tyre pressure warning light means the car thinks at least one tyre is well below its set pressure. Stop somewhere safe, check all four with a gauge, and inflate them cold to the figure for the load.
- A light that flashes a number of times at start-up and then stays on usually means a fault in the monitoring system, such as a dead sensor, rather than a low tyre. The DVSA MOT manual describes exactly this pattern.
- If the light comes back within days, usually a tyre is losing air: a nail, a valve or the bead. If the gauge shows all four correct when cold and it still returns, suspect a failing sensor. If it never clears with the pressures right, a sensor needs reading, replacing and relearning to the car.
- On passenger cars first used from 1 January 2012, a TPMS that is malfunctioning or obviously not working is a major MOT defect. A lamp that may only be showing low pressure gets an advisory.
The amber tyre-shaped symbol with an exclamation mark means your tyre pressure monitoring system (TPMS) thinks at least one tyre is well below its set pressure. Stop somewhere safe and check all four tyres with a gauge. Then inflate them to the figure on the door-pillar sticker or in the handbook. If the light flashes a number of times at start-up and then stays on, the likely cause is a fault in the system, such as a failed sensor, not a low tyre.
Most of the time a gauge, an air line and a short drive (plus a reset on some cars) put it out. This guide explains how to read the light, what to do in the next ten minutes, why it comes back, what the MOT actually checks, and when it is a sensor job rather than an air job.
What does the tyre pressure warning light mean?
Every new passenger car registered in GB since November 2014 has had to carry a tyre pressure monitoring system that warns the driver when a tyre loses pressure. That rule comes from Regulation (EC) No 661/2009, Article 9(2), as retained in GB law. The November 2014 deadline is set in Article 13. The MOT check reaches further back, to cars first used from 1 January 2012 (see the MOT section). New models sold from November 2012 already had to have TPMS, as TyreSafe notes. The rule does not say how the system must work. That is why some cars use sensors in the wheels and others use the ABS (more on that below).
The symbol itself, as Toyota UK describes it, looks like the cross-section of a tyre with an exclamation mark inside. Some cars show a car outline with the low tyre highlighted, or a message in the driver display, instead. If yours shows it in red rather than amber, check your handbook for what that colour means on your car. On a motorway, National Highways treats a red or amber warning light the same way: leave at the next exit or services.
What matters more than the picture is how the light behaves. The DVSA's MOT inspection manual describes the normal pattern: the lamp lights briefly when the ignition goes on and then goes out; it stays on if the system has detected a pressure loss; and "in the event of a system malfunction, the lamp may flash a number of times and then remain on".
| What you see | What it usually means | What to do |
|---|---|---|
| Solid light that came on while driving | One or more tyres has dropped well below its set pressure | Ease off, stop somewhere safe, look at the tyres, then gauge all four |
| Solid light on a cold morning that goes out later | A tyre was already low and the cold pushed it under the warning point | Top up to the cold figure; the warning was real |
| Flashes on start-up, then stays on | A fault in the system: a dead or unrecognised sensor, or a system error | Check pressures by hand, then have the sensors read |
| Comes on, goes off, comes back over days | A slow leak, or a sensor that is starting to fail | Note which tyre keeps dropping; if none does, suspect the sensor |
| On straight after new tyres, wheels or the spare | A sensor damaged or not relearned, an indirect system not reset, or a wheel with no sensor | Ask the fitter to read the sensors, or have them read at the car |
Do not read too much into the exact pressure that sets it off. The warning point varies from car to car. On many cars it is around a quarter below the recommended pressure, according to commercial guides such as the RAC. A tyre that low is already affecting the car: the Highway Code, Annex 6 says "your brakes and steering will be adversely affected by under-inflated or over-inflated tyres".
What should you do when the tyre pressure light comes on?
- Ease off and stop somewhere safe. On the way, notice whether the car pulls, vibrates or feels vague. It is "not recommended to drive with a TPMS light on", and you should stop and check the pressures by hand, says TyreSafe. On a motorway, leave at the next exit or services. With a red or amber warning light, you should "leave the carriageway at the next exit or pull into a service area if possible", in the words of National Highways. Our guide to a tyre pressure warning on the motorway covers that case in full.
- Look at all four tyres. A tyre that is visibly flat, cut or bulging means you should not drive on; see whether it is safe to drive on a flat tyre.
- Check every tyre with a gauge, including the ones that look fine. In our experience, a modern tyre can be well down and still look normal. Check "when tyres are cold", the Highway Code says, because "warm or hot tyres may give a misleading reading". If you have just driven, expect a reading above the true cold figure. Our step-by-step guide on how to check tyre pressure shows how.
- Inflate to the figure for your car and your load. It is on a placard on the driver's door sill, inside the fuel filler flap or in the handbook. The figure goes up with the load: "the more passengers or luggage, the higher the pressure will need to be", says TyreSafe. If your car monitors the spare, check that too.
- If you have just driven, only add air. As practical advice, top up any tyre that reads below the placard figure to at least that figure. Never let air out of a warm tyre. Then recheck all four cold the next morning, as the Highway Code advises.
- Reset if your car needs it, then drive. On most vehicles the light goes off by itself once the system confirms the readings are right, sometimes after a short drive, says Toyota UK. Others need a button or menu reset first. After a reset, drive normally for around ten minutes while the system recalibrates, the RAC advises. Your handbook gives the exact steps for your car.
How do you reset the tyre pressure light?
That depends on which kind of TPMS your car has. Goodyear sets out the difference plainly:
- Indirect TPMS has no sensors in the wheels. It uses the ABS wheel speed sensors, because an under-inflated tyre "begins to rotate faster than expected". It "requires resetting after tyre maintenance", in Goodyear's words, meaning inflation, rotation or new tyres. Set all four pressures first, then use the reset button or the vehicle settings menu and drive. The button is often under the steering wheel, Goodyear notes; otherwise the handbook shows where it is.
- Direct TPMS has a battery-powered sensor on the inside of each valve that measures the actual pressure. It "does not require a reset following tyre inflation or rotation", according to Goodyear. On most vehicles the light switches off automatically once the tyres are correct, though some need a manual procedure from the handbook (Toyota UK). A failed sensor is different: it "may need to be replaced and reprogrammed to communicate with the vehicle's control module".
Why is my tyre pressure light on when my tyres are fine?
First make sure they really are fine: check with a gauge, not by eye. If the readings match the placard, the usual explanations are:
- The system has not been reset, or not driven far enough, since you inflated the tyres.
- The pressures were set hot. Air added straight after a drive reads higher than it will be once the tyre cools, so a tyre can still be low the next morning.
- The spare is low, on cars that monitor it. The spare is easy to forget.
- A sensor has failed. TyreSafe says sensors "can become faulty or fail completely as a result of weather damage, corrosion or accidental damage caused when changing tyres", and their batteries eventually run out. A flashing-then-solid light points this way.
- The wheels have changed. Toyota explains that the control module "is designed to recognise and communicate with only one set of wheels at a time", so a winter set or replacement wheels need the module reprogrammed.
Why is the tyre pressure light still on after I put air in it?
Split it into two cases, because they have different causes.
It went out, then came back within hours or days. Usually a tyre is losing air and the light is doing its job. If the gauge shows all four correct when cold and it still returns, suspect a failing sensor. The common causes of a leak are a nail or screw in the tread, a leaking valve or valve core, or a bead leak where the tyre meets a corroded rim. Check which tyre has dropped and read our guides to a slow puncture and to a nail in the tyre. Topping up only buys time. A tyre that is repeatedly run low can be damaged inside, and the BTMA's guidance on repairs to BS AU 159 lists "under-inflation/deflation damage" as a reason a tyre must not be repaired.
It never went out at all. The system probably needs a reset, the reset was done before the pressures were right, or one sensor is not reporting. A sensor that is not reporting will not clear however much air you add. How long the light takes to go off varies by car; if it is still on after the drive your handbook describes, stop adding air and have the sensors read.
Why does the tyre pressure light come on when it is cold?
Because cold air takes up less room. Toyota UK puts it simply: "air contracts as temperatures fall, which can reduce tyre pressure", and the light often appears in colder weather "particularly if tyre pressures were already close to the minimum".
Some guides suggest driving for a while so the tyres warm up and the light goes out. That makes the light go away without fixing anything. The Highway Code tells you to check pressures cold because warm tyres mislead, so a tyre that only reaches its figure once warm is under-inflated. Top it up to the correct cold pressure, and if it is low every cold morning, check it again in a week: a tyre that keeps dropping has a leak.
Tyre pressure warning light after new tyres, new wheels or fitting the spare
A light that appears straight after tyre work is common, and it is almost always one of these causes:
- A sensor knocked or damaged while the tyre was being changed.
- A new sensor that has not been programmed and relearned to the car.
- An indirect system that was not reset for the new tyres.
- Wheels swapped for a set without sensors, or with sensors the car has not learned.
TyreSafe notes that many manufacturers recommend renewing the valve cap and core components every time a tyre is changed, and that a replacement sensor may need programming "using specialist diagnostic equipment".
The spare is a special case. Fit a wheel without a TPMS valve, such as the spare after a puncture, and the light will stay on; the system is not damaged by it, Toyota says. Expect the light to stay lit until the repaired or new tyre is back on that corner. Refit the repaired or new tyre on its sensored wheel before any MOT.
If you have been left with the light on after tyre fitting elsewhere, we can read the sensors, find the faulty one and carry out TPMS sensor replacement at your car, programmed and relearned at the car where the model allows.
Can you drive with the tyre pressure warning light on?
With a solid light, drive only as far as the nearest safe place to check and inflate the tyres. The law does not mention the lamp, but it does cover the tyre: regulation 27 of the Construction and Use Regulations 1986 says a vehicle must not be used on a road if a tyre "is not so inflated as to make it fit for the use" it is being put to. The light is the car telling you that may no longer be true.
How long can you go with a tyre pressure warning?
There is no safe mileage, because the light does not tell you how fast the tyre is losing air. Check which tyre it is at that first safe stop, not later in the day. If the gauge shows it fine after a top-up, carry on and check again the next morning.
With a flashing-then-solid fault light, the fault does not affect how the car drives, but the system is no longer watching your tyres. TyreSafe stresses that TPMS "should not replace regular, manual tyre checks", and with a fault that becomes your only check: gauge the tyres every few days until it is repaired. On run-flat tyres this matters more. A run-flat is built to keep going for a limited period after a puncture, at no more than 50 mph and with a limited load. That is why TyreSafe says run-flats should only be fitted to cars with a TPMS.
Is the tyre pressure warning light an MOT failure?
It can be, but not every lit lamp fails. The DVSA MOT inspection manual, section 5.2.3, is precise:
- The TPMS check is "for M1 vehicles first used on or after 1 January 2012", meaning passenger cars. Goods vans are outside this particular check.
- A TPMS "malfunctioning or obviously not working" is a major defect, which fails the test.
- A lamp that stays on because the system has detected low pressure "does not automatically mean the system has a malfunction". If the tester cannot tell whether the lamp shows a fault or just low pressure, the manual says an advisory should be added instead.
- An "obviously under-inflated" tyre is a separate minor defect.
So set the pressures correctly before the test, and if the light still shows a fault, get the sensor fixed first. Our list of common tyre MOT failures covers the other tyre checks.
Can you turn the light off permanently?
You should not. TyreSafe is blunt that a sensor should never be "removed and replaced with a 'standard' non-TPMS type valve", because that reduces your safety and "will also result in your car failing its MOT". Covering or coding out the warning leaves you with the same problem: no warning when a tyre goes down.
Direct vs indirect TPMS, and how long sensors last
| Direct TPMS | Indirect TPMS | |
|---|---|---|
| How it measures | A sensor inside each wheel reads the actual pressure | ABS wheel speed sensors spot a tyre turning faster than the others |
| Tells you which tyre | On many cars, which tyre is low | May not show which tyre, so gauge all four |
| After inflating | Usually clears itself after a short drive | Must be reset by you, then driven |
| What usually goes wrong | Sensor battery, sensor damage, valve seals | A reset forgotten or done with a tyre low |
| At a tyre change | Sensors checked with a TPMS tool; new ones programmed | System reset for the new tyres |
How long do TPMS sensors last?
Direct sensors run on a sealed battery, and estimates of its life differ. They "typically last for between 5 and 10 years", according to TyreSafe. Toyota puts it at around ten years, with a battery that cannot be replaced. Goodyear says five to seven. So treat any sensor past five years old as a candidate when the light flashes. When one battery goes, bear in mind that the other sensors on the car were usually fitted at the same time.
What a fitter checks when the light will not go out
This is how we work through a TPMS warning at the car, in order:
- Read every sensor before touching a tyre. A TPMS tool shows each sensor's ID, the pressure it reports and its battery state, and whether it is transmitting at all. That separates an air problem from a sensor problem in minutes.
- Gauge each tyre and compare. A sensor reading that disagrees with the gauge is a sensor fault; a tyre that agrees and is low is a leak.
- Find the leak. Tread for nails and screws, the valve core and the seal and nut of the sensor valve, and the bead where the tyre meets the rim, where corrosion on alloys can let air past.
- Look inside a tyre that has run low. A tyre driven soft can be damaged on the inside, which decides whether it can be repaired to BS AU 159 or has to be replaced.
- Replace and relearn. The failed sensor or valve parts are renewed, and the new sensor is programmed and relearned to the car, at the car where the model allows. Some cars need the control module reprogrammed through the diagnostic port.
A hypothetical example: sensor or tyre?
Say the placard figure is 2.4 bar and the dash shows the front left at 1.7. If a gauge on that tyre also reads 1.7, the sensor is telling the truth and the tyre is losing air. If the gauge reads 2.4 and the dash still shows 1.7, or shows no reading at all for that wheel, the air is fine and the sensor is the problem.
Need someone to come to you?
If the light is down to low pressure and a top-up fixes it for good, you do not need us. If a tyre keeps dropping, or the light is telling you a sensor has failed, we come to the car at home, at work or parked at the kerb, anywhere we cover across London and the surrounding counties. We work 24 hours a day, typically arrive within 30 to 60 minutes, and there is no out-of-hours surcharge. If you are on a motorway, leave it first; once the car is somewhere safe, we come to it.
We can find and fix a puncture, repaired to BS AU 159, renew a leaking valve with a tyre valve replacement, or replace a failed tyre pressure sensor. If the tyre is past repair, we fit a new one the same day.
When you call or message, these details tell us what to bring:
- How the light behaves: solid, flashing then solid, or on and off.
- Which tyre, if the dashboard shows one, and the readings if it shows them.
- Recent tyre work: new tyres, different wheels or the spare fitted, and when.
- What a top-up did: whether the light went out, and how long before it came back.
- The car and where it is: make, model, registration and a postcode.
Tell us whether it is solid or flashing and which tyre it shows. We read the sensors at your car and fix the leak or replace the faulty sensor, typically arriving within 30 to 60 minutes.
Sources
Checked on 2 October 2026. Legal, MOT and safety points come from the primary and industry sources below; manufacturer guidance is used only for how systems generally behave, and your handbook overrides it for your car. The fitter's checks describe how the job is done.
- MOT inspection manual: 5. Axles, wheels, tyres and suspension, section 5.2.3 (DVSA, GOV.UK)
- The Highway Code, Annex 6: vehicle maintenance, safety and security (GOV.UK)
- The Highway Code, rules 274 to 287: breakdowns and incidents (GOV.UK)
- Driving on motorways (National Highways)
- Road Vehicles (Construction and Use) Regulations 1986, regulation 27 (legislation.gov.uk)
- Regulation (EC) No 661/2009, Articles 9 and 13 (legislation.gov.uk)
- What is a Tyre Pressure Monitoring System (TPMS)? (TyreSafe)
- Tyre pressures explained (TyreSafe)
- Minor repairs to passenger car and light van tyres (British Tyre Manufacturers' Association)
- Tyre pressure warning light: what it means, what to do (Toyota UK)
- What is TPMS and how does it work? (Goodyear)
- Tyre pressure monitoring system (TPMS) guide (RAC, used for the typical warning point and reset drive time)
Photo: Andrea Piacquadio on Pexels
Frequently asked questions
Check with a gauge first, because in our experience a tyre can be well down and still look normal. If the cold pressures are right, the usual causes are a reset not done, a low monitored spare, a failed sensor or wheels the car has not learned; see light on but the tyres look fine.
With a solid light, only as far as the first safe place to check the tyres; on a motorway, leave at the next exit or services. With a flashing-then-solid fault light the fault does not affect how the car drives, but you must gauge the tyres yourself until it is fixed; see can you drive with it on.
There is no safe mileage, because the light does not show how fast a tyre is losing air. Stop at the first safe place, gauge all four tyres and inflate them there or at the nearest air line.
Your handbook says what a red light means on your car, so check it there. Either way, stop somewhere safe and gauge all four tyres. On a motorway, National Highways treats a red or amber warning light the same way: leave at the next exit or pull into a service area.
A wheel without a TPMS valve, such as a spare fitted after a puncture, leaves the light on without damaging the system, Toyota says. Expect it to stay lit until the repaired or new tyre is back on that corner, and refit that tyre on its sensored wheel before any MOT.
A light that flashes a number of times when you start the car and then stays on usually means a fault in the monitoring system, such as a dead or unrecognised sensor, rather than a low tyre. The DVSA MOT manual describes this pattern as a system malfunction.
If it went out and came back, usually a tyre is losing air; if the gauge shows all four correct when cold and it still returns, suspect a failing sensor. If it never went out, the system needs a reset or a sensor is not reporting. See still on after air, or keeps coming back.
It varies by car. Many clear once the pressures are right, sometimes after a short drive. Indirect systems need a reset first, and after a reset the RAC says to drive normally for around ten minutes. Your handbook gives the exact steps; see how to reset the light.
On passenger cars first used from 1 January 2012, a TPMS that is malfunctioning or obviously not working is a major defect; a lamp that may only be showing low pressure gets an advisory. See is it an MOT failure.