What does it mean?
C1207 is a Chassis (ABS, traction control, steering) fault code. It indicates: Wheel Speed Sensor Rear-LH Range / Performance / Intermittent .
Symptoms
- ABS and stability control lamps that light while driving rather than at key-on
- Unexpected ABS or traction control activation at low speed, often just as the car comes to a stop
- Rear left wheel speed lagging, spiking or dropping to zero in live data while the other channels agree
- A rumbling or humming noise from the rear that changes with speed, if a bearing is the underlying cause
- Fault that clears on restart and comes back after a certain distance, speed or road surface
Likely causes
- Tone ring rusted, cracked or partly missing teeth, usually because of long term salt exposure at the rear
- Sensor tip contaminated with brake dust or ferrous debris
- Corrosion behind the sensor in its bore pushing it out and widening the air gap
- Worn rear wheel bearing letting the hub move under load so the signal fades and returns
- Intermittent high resistance in a corroded connector or a partly broken conductor in the trailing arm section of the loom
- Tyre size, tread depth or pressure at that corner noticeably different from the others
- Sensor output weakening with age so it drops below the module's threshold at certain speeds
How to fix it
- Record live data from all four wheel speed channels on a road test and identify the channel that misbehaves
- Compare tyre sizes, tread depths and pressures across the axle before dismantling anything
- Remove the sensor, clean the tip and the bore, and remove any corrosion that was holding the sensor out of position
- Rotate the wheel by hand and inspect the tone ring right around for rust flaking, cracks and damaged teeth
- Check rear wheel bearing play and listen for roughness while the hub is turned
- Inspect and wiggle test the sensor lead along the trailing arm, where salt damage is most common, with live data displayed
- Replace a weak sensor or a hub and bearing assembly with a damaged tone ring, then confirm all four speeds track evenly on a road test