What does it mean?
C1210 is a Chassis (ABS, traction control, steering) fault code. It indicates: Right Rear Wheel Speed Sensor Signal Range/Performance/Intermittent .
Symptoms
- ABS warning lamp on, usually together with the traction and stability control lamp
- ABS is switched off; the brakes still stop the car but wheel lock-up is no longer prevented
- Brief, unwanted ABS pulsing at low speed on dry roads just before the code stores
- Traction control, stability control and hill-hold assist become unavailable
- Erratic speedometer or trip computer readings on vehicles that use rear wheel data
- Fault comes and goes over bumps or in wet weather
Likely causes
- Metal filings, rust flakes or hardened brake dust stuck to the magnetic tip of the right rear wheel speed sensor
- Excessive air gap between the sensor and the tone ring, caused by a loose sensor or corrosion building up behind it in the bore
- Cracked, chipped or rust-swollen tone ring on the right rear hub or drive shaft
- Chafed or stretched sensor harness along the trailing arm that opens intermittently as the suspension moves
- Water or salt in the right rear wheel connector or at the body pass-through, raising circuit resistance
- Play in the right rear wheel bearing letting the hub move and change the sensor gap
- Sensor element that drops out once it warms up
How to fix it
- Graph all four wheel speeds on a road test and find where the right rear reading drops out, spikes or lags the others
- Remove the sensor and inspect the tip and its bore for metal debris, rust scale and packed brake dust; clean and refit to the specified torque
- Inspect the tone ring for missing, chipped or corrosion-lifted teeth and for dirt packed between the teeth
- Wiggle-test the harness and connector at the trailing arm and body pass-through while watching live data
- Measure sensor resistance and output, AC millivolts for a passive sensor or a square wave for an active one, and compare with the opposite wheel
- Check right rear wheel bearing play; replace the bearing when the sensor or encoder is built into it
- Replace the sensor only after wiring, air gap and tone ring check out, then clear the code and road-test above the ABS self-test speed