A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- The sensor supply wire shorted to ground or to positive
- The sensor connector: dirt, water, corroded pins
- The sensor wire is chafed or broken — in the wheel arch, by the shock absorber or at the bend near the hub
- The ABS unit: it supplies power to the sensors
What you can do yourself
- With this fault ABS usually switches off: the ordinary brakes still work, but without ABS the wheels can lock. Brake smoothly and leave a bigger gap, especially on slippery roads.
- The ABS unit powers the sensor. If supply codes show up for several wheels at once, look for a common cause: the ABS unit connector, its ground and its fuse.
- Inspect this wheel’s sensor and its wire up to the connector: dirt, corroded pins, chafed insulation. Clean the connector, remove the sensor and clean its tip and its seat of dirt and rust.
Stop and don’t drive on if:
- The red brake light is on, or the brake pedal feels soft or sinks
- The steering became very heavy, or the car pulls to one side when braking
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
If the scan tool shows the code with a suffix after a dash (for example, C0031-1D), that’s the fault detail: 01 — general electrical failure, 1D — circuit current out of range, 29 — invalid signal, 2F — erratic signal, 62 — signal doesn’t match the others.
The explanation comes from the error code reference in the AvtoElektrik PRO app.