Tyre pressure light (TPMS) on: what to do
Updated:
The tyre pressure light means at least one tyre is under-inflated. Check all four tyres and inflate them to the figures on the door pillar or fuel flap sticker, then reset the system. If the light comes back quickly, a tyre probably has a puncture. If the light flashes at first and then stays on, the fault is usually in the system itself, for example a sensor.
Why it comes on with the first frosts
Air contracts in the cold and pressure drops by roughly 0.1 bar for every 10 degrees. A tyre set correctly in summer can be at the warning limit on a cold morning. Inflate tyres cold, not right after a long drive.
Two kinds of system
Direct systems have a pressure sensor in every wheel. Sensor batteries typically last several years, and when one runs flat the sensor is replaced. When changing to the other set of wheels, those wheels need sensors too, or the car has to be set up without them.
Indirect systems have no sensor in the wheel: they compare wheel speeds through the ABS sensors. After inflating or changing tyres, reset the system from the menu or button, or it will learn the wrong pressure.
Light flashes, then stays on
On many cars this means the system can't hear one of the sensors: a flat battery, a broken sensor or no sensor in the wheel at all. Tyre pressure may be perfectly fine. The fault code shows which wheel isn't responding.
Want a definite answer?
Bring the car to our workshop in Estonia for diagnostics. We read the fault codes, test the sensors and tell you what is wrong.
Frequently asked questions
Can you drive with the tyre pressure light on?
Gently, to the nearest air pump, yes. If a tyre is visibly flat or the car pulls to one side, don't drive: change the wheel. Driving on a flat ruins the tyre quickly.
How do you reset the tyre pressure system?
Inflate all tyres correctly, then choose tyre pressure reset in the car's menu or press the reset button. The owner's manual shows where. On some cars the light goes out by itself after a short drive.
What pressure should the tyres be?
It is on the sticker on the door pillar or fuel flap. There is often a separate, higher figure for a fully loaded car.
Will a tyre pressure light fail the inspection?
If the car has a tyre pressure monitoring system, it must work. A lit or flashing light can be noted as a defect, so fix it beforehand.
How much does a new sensor cost?
It depends on the sensor and the car. Diagnostics cost €45/h, the price depends on the job. We first read which wheel's sensor isn't responding.