TPMS warning light: what it means and what to do
A tyre pressure warning light is worth taking seriously, but it isn't automatically a puncture. Here's how to work out which it is.
TPMS (Tyre Pressure Monitoring System) has been mandatory on new UK cars since 2012, and it's designed to catch pressure loss before it becomes a visible problem or a safety issue. When the warning light comes on, it means the system has detected a pressure reading outside the expected range on at least one wheel — not necessarily a puncture.
The most common causes
A drop in outside temperature
Tyre pressure falls roughly 1 psi for every 5–10°C drop in temperature. A cold snap overnight is one of the most common, and least serious, causes of a TPMS light.
A slow puncture
A small nail or screw can leak air gradually over hours or days rather than causing an immediate flat — this is exactly the kind of loss TPMS is designed to catch early.
A faulty or low-battery sensor
Direct TPMS systems use a small battery-powered sensor inside each wheel, which can fail or run down over time (typically after several years) independent of the actual tyre pressure.
A wheel change without sensor recalibration
Fitting a spare, swapping to winter wheels, or a recent tyre change can occasionally leave the system needing a reset or recalibration to read correctly again.
What to do when the light comes on
Check all four pressures
Use a garage forecourt or home gauge to check every tyre against the correct pressure, found on a sticker inside the driver's door frame or in the handbook — not the number printed on the tyre sidewall itself, which is a maximum, not a recommendation.
Top up as needed
If one or more tyres are low, inflate to the correct pressure and see whether the warning clears (it may take a short drive for the system to re-read).
Inspect for a puncture
If a tyre keeps losing pressure after being topped up, check the tread and sidewall for anything visible, and treat it as a likely puncture needing assessment.
Get it checked if the light persists
If all pressures read correctly and the light stays on, the sensor itself may be faulty — this needs a proper diagnostic check rather than guesswork.
Frequently asked
Is it safe to keep driving with the TPMS light on?
For a short distance to check and correct pressures, generally yes — but don't ignore it long-term. Persistent low pressure affects handling, fuel economy and tyre wear, and can mask a genuine slow puncture.
Why does my TPMS light come on every winter?
Cold weather is one of the most common triggers — tyre pressure drops with temperature, and a tyre correctly inflated in summer can read as under-pressure once temperatures fall. Check and top up pressures at each significant temperature change.
Can a TPMS sensor be replaced during a tyre change?
Yes — if a sensor is faulty, it's typically replaced while the tyre is already off the wheel, which is the most efficient time to do it.
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