Tyre pressure warning light: causes and the faults that trigger it

1. 1. Slow air loss through the valve or small leaks

   Common cause

   RACE explains that a gradual loss of air can come from a worn valve or small leaks. It is fixed by topping the pressure back up.^[1]

   Faults with with tyres and wheels

2. 2. Cold weather or temperature changes

   Common cause

   According to RACE, low temperatures reduce the air pressure inside the tyres, so the pressure can drop in the cold and turn the warning light on.^[1]

   Faults with with tyres and wheels

3. 3. Puncture or damage to the tyre or wheel rim

   Possible cause

   Autopista recommends visually inspecting the tyres for an obvious puncture before adding air, and advises going to a specialist if there is visible damage to the tyre or rim or if the car vibrates abnormally.^[4][5]

   Faults with with tyres and wheels

4. 4. System not recalibrated after inflating or changing tyres

   Common cause

   RACE says that after changing tyres or swapping wheels between axles, some cars need the system recalibrating, and in another article it reminds readers that after inflating you must reset it with a button. Coches.com adds that the indirect system must be recalibrated after changing the pressure or a wheel, and Michelin that a professional must readjust it if the tyre size changes.^[1][2][3][6]

   Faults with with tyres and wheels

5. 5. Flat battery in a wheel sensor

   Possible cause

   Sensors fitted in the wheels have an internal battery with a limited life: RACE and Michelin speak of 5 to 7 years and Coches.com of around five, and in that case the whole sensor has to be replaced.^[1][3][6]

   Faults with with tyres and wheels

6. 6. Sensor damaged by a wheel knock

   Uncommon

   Coches.com warns that knocks from the wheel against a kerb can damage the sensors and should be avoided.^[3]

   Faults with with tyres and wheels

7. 7. Fault in the TPMS system itself

   Uncommon

   RACE describes that if the light keeps flashing even though the pressure is correct, the system is not working properly and needs a professional diagnosis.^[2]

1. Measure the pressure of all four tyres when cold, before driving, and compare it with the manufacturer's sticker (usually on the driver's door or inside the fuel flap) or with the manual.^[5][8]
2. Inspect the tyres and wheel rims for an obvious puncture, a bulge or any visible damage.^[1][5]
3. Adjust the pressure and reset or recalibrate the system with its button or from the car's menu, according to the manual.^[1][2][4]
4. Drive a few kilometres or a few minutes so that the system rechecks the values and switches off the warning.^[1][4]
5. If the light flashes, does not go out after the reset, there is visible damage or the car vibrates, have it diagnosed at a garage: it could be a sensor or the system itself.^[2][4]
6. Even if your car has TPMS, measure the pressure once a month: Michelin points out that the system only warns you once around 20% of the air has been lost.^[6]

Urgency: Monitor

If the warning is caused by a small loss of pressure, RACE says you can normally drive to a service station to check the inflation. It should not be ignored: with low pressure, braking distance increases, grip is reduced, fuel consumption goes up and wear accelerates. If there is visible damage to the tyre or rim or the car vibrates abnormally, Autopista recommends going to a specialist.^[1][4]

1. • High severityFrequency: OccasionalVolkswagen Caddy VBulges or tears in the inner sidewall of the Caddy's tyresGradual or sudden loss of pressure in a tyre.

   Source for the symptom in the Volkswagen Caddy V^[9]

2. • Medium severityFrequency: OccasionalFiat Doblò IIIInaccurate tyre pressure warning caused by incorrect ESC codingAccording to the source, the system may fail to warn or warn late (with a 20% pressure drop) or, conversely, warn for no reason with a pressure loss of only 10%.

   Source for the symptom in the Fiat Doblò III^[10]

3. • Medium severityFrequency: OccasionalToyota ProAce CityIncorrect calibration of the indirect tyre pressure monitoringThe low pressure warning light may fail to come on, come on late or give a false warning when the tyres are under-inflated.

   Source for the symptom in the Toyota ProAce City^[11]

4. • High severityFrequency: RareOpel Mokka BDamaged tyres at the final brake inspection (built October 2024)No prior symptom described; the risk is sudden pressure loss.

   Source for the symptom in the Opel Mokka B^[12]

5. • Low severityFrequency: OccasionalHonda HR-V IIFalse tyre pressure and oil level sensor warningsThe tyre pressure warning light comes on intermittently without any real loss of pressure.

   Source for the symptom in the Honda HR-V II^[13]

6. • Low severityFrequency: OccasionalKia XCeedElectronics faults: central screen, tyre pressure sensors and central lockingThe tyre pressure sensors can give wrong readings or stop working intermittently.

   Source for the symptom in the Kia XCeed^[14]

7. • Low severityFrequency: RareHonda Jazz IIIOver-sensitive tyre pressure sensors on the Honda Jazz IIILow pressure warning that appears in hot weather even though the pressure is correct.

   Source for the symptom in the Honda Jazz III^[15][16]

8. • Low severityFrequency: RareMazda CX-7Electronic faults in the tyre pressure monitoring systemThe source speaks of electronic faults in the tyre pressure monitoring, the system that manages the pressure warning; it does not describe how they show up.

   Source for the symptom in the Mazda CX-7^[17]

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