TPMS Tyre Pressure Sensors

Why tyre pressure sensors fail

TPMS sensors sit inside the tyre on the wheel and run on their own battery. The problems seen most often are:

• Battery at end of life — typically five to ten years. The battery is not replaceable, so the whole sensor is changed. When one has gone, the others are usually close behind.
• Physical damage during a tyre change — the sensor body or valve stem stressed by the machine.
• Corrosion — on aluminium valve stems, particularly where roads are salted.
• A sensor never relearned — a new sensor is invisible to the vehicle until the relearn procedure is carried out.
• Position confusion after rotation — the system no longer knows which wheel is where.

When the warning light will not clear

If the light stays on after you have corrected the pressures, work through it in this order: set all four tyres and the spare to the correct value, run the relearn with the tool, and if it still will not clear, read each sensor individually to find the one that does not answer. A sensor that does not answer has a flat battery or is damaged.

What a programmable sensor is

Original sensors are vehicle specific, which means holding stock for every make. A programmable sensor such as the Autel MX-Sensor is a single part that the tool programs to the protocol of whichever vehicle it is going on. For tyre shops and workshops it cuts the stock burden considerably.

Cloning and relearning

There are two routes. If the old sensor can still be read, its ID is cloned and the vehicle notices nothing, so no relearn is needed. If it cannot be read, the new sensor is given a fresh ID and taught to the vehicle with the tool. The TS508WF supports both.