TPMS
Your TPMS light is on. What it usually means
The amber horseshoe on the dash is a pressure story until proven otherwise. Work through it in this order before you buy four new sensors.
TPMS exists to warn you of under-inflation. The first job is a gauge, not a parts counter. Check all four tyres cold, including the one that looks fine, and the spare if the car has a sensor in it.
Three common causes
- A seasonal temperature drop. Pressures fall in cold weather and the light arrives on the first frosty commute.
- A slow puncture from a screw or a weeping valve. The tyre looks normal in the evening and soft in the morning.
- A dead sensor battery. Sensors are sealed and last roughly five to ten years. They fail one at a time, often just after a tyre has been removed.
If pressures are correct and the light remains after a short drive, the car may need a relearn, a TPMS service kit, or a new sensor. We read the system on site. Indirect systems, which have no sensors in the wheels, usually only need the pressures set and a dashboard reset.
Ignore the light and you will also miss a real puncture. If the car is already sitting on the rim, treat it as a roadside job and call rather than using the online diary.