What does it mean?
C1246 is a Chassis (ABS, traction control, steering) fault code. It indicates: Wheel Speed Sensor Output Signal Error . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms
- ABS and stability lamps on, often after driving rather than at key-on
- Unexpected ABS activation at very low speed or a brief brake grab when stopping
- ABS dropping out above or below a certain speed
- Wheel speed trace on the scan tool ragged or lagging compared with the other wheels
- Occasional speedometer flicker on vehicles that use this signal
- Code returns after a road test even though it clears at key-on
Likely causes
- Dirty sensor tip or a wide air gap, weakening and distorting the waveform
- Tone ring with corroded, chipped or unevenly spaced teeth
- Sensor internally failing, with output that collapses when hot or at higher speeds
- Chafed sensor wiring or a broken shield, letting electrical noise into the signal
- Corroded connector or moisture in the wheel arch plug
- Worn wheel bearing letting the gap vary as the wheel turns
- Sensor harness routed against an ignition or high current cable after a previous repair
How to fix it
- Graph all four wheel speeds during a road test and identify which trace is ragged or drops away
- Scope the suspect sensor output and judge the waveform quality against the opposite wheel
- Remove the sensor and clean the tip and bore, then check the air gap and refit correctly
- Inspect the tone ring for corrosion, uneven or damaged teeth and packed debris
- Check the sensor harness routing, shielding and ground, especially where it has been repaired before
- Check the wheel bearing for play and roughness
- Replace the sensor once the ring, wiring and gap are proven good, then confirm a clean signal on a road test