// Tyre pressure monitoring

TPMS relearn: why the light stays on, and how to clear it properly

New tyres, a wheel rotation or a winter set, and the tyre-pressure light won't go out even though the pressures are right. That is almost always a relearn problem, not a sensor problem.

What the car is actually complaining about

Every TPMS sensor transmits its own unique ID along with pressure and temperature. The car keeps a list of which IDs belong to it and, on many models, which wheel each one sits on.

Swap wheel sets and the car hears IDs it doesn't know. Rotate tyres and the IDs are right but the positions aren't. Replace a sensor and one ID is new. In each case the pressures can be perfect and the light stays on, because the car cannot match what it hears to what it expects. A relearn fixes the list.

The three relearn methods

MethodHow it worksTool needed
AutomaticThe car learns the sensors itself after a period of drivingUsually none, sometimes a tool to confirm
StationaryThe car is put into learn mode, then each sensor is woken in a set orderA trigger or TPMS tool to wake each sensor
OBDThe tool reads each sensor's ID and writes them to the car through the OBD portA TPMS tool with OBD relearn

Which one applies depends on make, model and year. A proper TPMS tool looks the procedure up for the car you select, which removes most of the guesswork.

315 MHz or 433 MHz

Sensors transmit on one of two frequencies. Broadly, cars built for North America use 315 MHz and cars built for Europe use 433 MHz, with exceptions both ways, especially on imports. A tool that covers both frequencies saves you from having to know in advance.

Sensor programming

When a sensor fails, there are two routes. Buy the original part and relearn it, or fit a programmable universal sensor and have a tool write the right protocol to it, often copying the old sensor's ID so the car never notices the change.

Programming is the step a basic trigger can't do. It needs a tool that supports the programmable sensors you are fitting; the Launch CRT5011 V2 we stock programs Launch RF sensors.

Trigger or full TPMS tool?

 Basic triggerFull TPMS tool
Wake sensorsYesYes
Read ID, pressure, temperature, batteryLimitedYes
Look up the relearn procedureNoYes
OBD relearnNoYes
Program sensorsNoYes, for supported sensors

One car with a stationary relearn: a trigger can do it. Several cars, OBD-relearn cars, or sensor replacements: a full tool is the one that actually finishes the job.

Check the basics first. A light that stays on can also mean a sensor with a flat internal battery, a damaged sensor after a tyre change, or pressures that are right cold but wrong for the car's placard. A TPMS tool that reads sensor battery and signal tells you which one it is before you start swapping parts.

Questions people actually ask

Why is my TPMS light on after new tyres?
Most often the car needs a relearn, or a sensor was damaged or left without its valve core seal during fitting. Read the sensors first; a tool will show whether each one is transmitting.
Do winter wheels need their own sensors?
If the car has direct TPMS and you want the system to keep working, yes. Each swap then needs a relearn, unless your car supports storing two sets.
How long do TPMS sensors last?
They run on a sealed battery that cannot be replaced, so they eventually stop transmitting. A tool that reads sensor battery status lets you see which ones are near the end.
Can I just ignore the light?
You lose the warning for a real puncture, and in many countries a lit TPMS warning is an inspection issue. It is worth fixing properly.

The tool this page is about.

Launch CRT5011 V2: 315/433 MHz, sensor reading, relearn and RF-sensor programming. €229, shipped free, 2-year warranty.

See it in the shop → Which tool do I need?