What does it mean?
C1222 is a Chassis (ABS, traction control, steering) fault code. It indicates: ABS Wheel-Speed Sensor System .
Symptoms
- ABS and traction control lamps on, sometimes only after driving a certain distance
- Stability control cutting in on a straight road or in gentle bends
- ABS activating at very low speed, for example on the last metre of a stop
- Fault appearing straight after a tyre change, hub replacement or spare wheel fitment
- Vehicle pulling to one side, or one wheel hot after a drive, when a brake is dragging
- Speedometer reading slightly off compared with actual speed
Likely causes
- Mismatched tyre sizes across an axle, or a space saver spare fitted
- Large difference in tread depth or tyre pressure between wheels
- One sensor reading low because of a wide air gap, debris on the tip or a dirty tone ring
- Damaged tone ring teeth, or a ring with the wrong tooth count fitted with a replacement hub
- Dragging brake or a seized caliper slowing one wheel slightly all the time
- Wheel bearing play that lets the sensor gap change as the wheel loads and unloads
- Different rolling radius after fitting non standard wheels or after a differential repair
How to fix it
- Graph all four wheel speeds at a steady speed and identify which wheel deviates from the rest
- Check tyre sizes, brands, pressures and remaining tread on all four corners, including any fitted spare
- Remove the suspect wheel and inspect the sensor tip, bore and air gap, then clean and refit correctly
- Inspect the tone ring for damaged teeth, corrosion and packed debris, and confirm the tooth count matches the other side
- Feel the wheels for uneven heat after a drive and check for a dragging brake or a seized caliper slide
- Check the wheel bearings for play and roughness
- Correct the mechanical cause first, then clear the code and confirm the wheel speeds track together on a road test