Direct vs Indirect TPMS Systems
There are two types of TPMS fitted to modern vehicles. Direct TPMS uses pressure sensors located inside each wheel that transmit real-time pressure readings to the vehicle's ECU. Indirect TPMS uses the ABS wheel speed sensors to detect changes in tyre diameter caused by pressure loss — a flat tyre rotates faster than a correctly inflated one — rather than measuring pressure directly.
Direct systems are more accurate and can typically show you which specific tyre is low. Indirect systems simply alert you that pressure has changed somewhere, without identifying which wheel. Knowing which type your vehicle uses helps you interpret the warning more effectively.
What Triggers the TPMS Light
The most common trigger is genuinely low tyre pressure — usually when one or more tyres falls 25% or more below the recommended level. A cold morning can be enough to bring a borderline tyre over the threshold, particularly in winter when ambient temperatures drop sharply overnight. Checking and correcting all four pressures often resolves the warning.
If the light comes on as a flashing symbol before settling to a constant glow, this typically indicates a sensor fault rather than a pressure issue. TPMS sensors have finite battery lives — usually between five and ten years — and the warning can signal that a sensor battery has died or that a sensor has been damaged, for example during a tyre change carried out without the correct equipment.
Can You Drive With the TPMS Light On?
If the light comes on while driving, reduce your speed carefully and check your tyre pressures at the earliest safe opportunity. Do not ignore a TPMS warning and continue at motorway speeds without investigation — even if the tyres appear visually normal, one could be losing pressure at a rate that makes continued driving genuinely hazardous.
A flashing TPMS light indicating a sensor fault, rather than a pressure issue, does not typically represent an immediate safety concern — but should be addressed. Triumph Mobile Tyres carries replacement TPMS sensors and can diagnose, replace, and reprogram sensors at your location.
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