What does it mean?
C1230 is a Chassis (ABS, traction control, steering) fault code. It indicates: ABS Hydraulic Valve Power Relay Circuit Short to Ground . 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 at key-on with no self test noise from the hydraulic unit
- Anti lock braking unavailable while normal braking is unaffected
- ABS fuse blowing when the circuit is energised on some vehicles
- Fault stored again as soon as the code is cleared, without moving the vehicle
- Additional valve or relay codes stored at the same time
Likely causes
- Harness pinched under a bracket or trapped by a fastener during previous work on the hydraulic unit or engine
- Insulation worn through where the loom crosses the inner wing or a suspension turret
- Water, salt or brake fluid inside the ABS module connector creating a leakage path to ground
- Relay coil shorted internally to its case
- Rodent damage to the loom in the engine bay
- ABS module output stage shorted to ground internally
How to fix it
- Check and load-test the ABS fuses, then unplug both the relay and the ABS module
- Measure resistance from the relay control circuit to ground with the harness isolated; a low reading proves the short is in the wiring
- Inspect the loom along the inner wing, hydraulic unit bracket and any point where it is clamped
- Look for rodent damage, crush marks and melted insulation and repair the affected section
- Dry and clean the module connector and check for brake fluid or moisture in the cavities
- Bench test the relay coil for insulation to its case
- Re-measure after the repair to confirm the short has gone, then replace the module only if the fault stays with a clean harness