Tire pressure light won't go out? Here's why — and what I'd do about it

Tire-pressure monitoring works on sensors inside each wheel. Each sensor is a small battery-powered radio transmitter with its own unique ID, and the vehicle's module keeps track of which ID is at which corner.

Fill a tire and the pressure is correct — but if the module is still holding old or rejected sensor data, it doesn't know that. It's looking for a signal it no longer recognises, so the light stays on. That's the difference between a pressure problem and a relearn problem, and it's the one most people never get told.

Rotation is the classic cause: the sensors physically moved corners, and the module's map now says the wrong wheel is where. New sensors come with new IDs the module has never seen. Both need a relearn, not more air.

This is where doing it yourself gets frustrating, because there is no single method:

I bring the tooling for all three. What's more, I confirm which procedure your vehicle uses before I come out, so nothing is left to chance in your driveway.

TPMS diagnosis and relearn, from $35. I read what your vehicle's tire-pressure module is actually reporting — a relearn that never happened, a sensor that has stopped transmitting, or the wrong tire size stored in the vehicle — and then I run the relearn your vehicle uses, where it is supported. The starting price is on this page because the job depends on the vehicle: some relearn from the driver's seat, some need a tool at each wheel. I confirm the price for your vehicle before I come out.

I come to you — your home, your office, wherever the car is parked. I plug professional equipment into the OBD port and read the module rather than guessing at your wheels, then I tell you what it says.

I diagnose sensors and perform relearns. I don't install sensors. If a sensor turns out to be dead — the battery inside a TPMS sensor does eventually fail — I'll spot it and tell you plainly. A relearn re-identifies the sensors you already have; it can't revive one that's stopped transmitting, and fitting a new sensor is a tire-shop job.

Some vehicles need a tire-size configuration as well after a wheel or tire change, not just a sensor relearn — the system has to be told the new size for the pressures and speed information to line up. If that applies to your vehicle, I'll tell you, and I can do it in the same visit. That's the Tire Size Recalibration service — $45, published like everything else I do.

It's one short visit at a published starting price, and it's the clearest window into how I work: I turn up when I say, I use professional equipment, and I show you what I'm doing rather than disappearing under the hood. If it turns out you need something else, you'll hear it from me straight — not as an upcharge.