What does it mean?
C1198 is a Chassis (ABS, traction control, steering) fault code. It indicates: ABS Hydraulic Valve Power Relay Circuit Open . 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, traction and stability control lamps on the moment the ignition is switched on
- Complete absence of the usual valve click and pump hum during the ABS self-test
- ABS never activates: the pedal remains hard and wheels lock in an emergency stop
- Normal braking feels entirely unchanged, so the fault only shows up in an emergency
- Traction control, hill-start assist and electronic brake force distribution are unavailable
Likely causes
- Open high current fuse feeding the ABS hydraulic unit
- Relay coil burnt open or relay pins not contacting an oxidised, spread socket
- Conductor fractured inside the insulation, typically where the loom flexes near the hydraulic unit
- ABS module connector pin corroded, bent or pushed out of the housing
- Ground connection for the hydraulic unit or module broken, loose or corroded
- Wire cut, pinched or left unplugged during previous work in the engine bay
- Internal open circuit inside the ABS control module at the valve supply input
How to fix it
- Meter test every ABS fuse including the high current fuses rather than checking them visually
- Read all stored codes; an entire set of valve circuit codes together means the shared supply is missing, not the individual coils
- Verify the relay is the right part, fully seated, and substitute a known good one if available
- With the ignition on, measure voltage on both sides of the relay socket to determine which side of the circuit has failed
- Perform section by section continuity tests from the fuse output through to the ABS module connector
- Inspect the module connector for water damage and displaced terminals, and clean and retighten the ABS ground point
- Repair the open circuit first; ABS module repair or coded replacement is the last step after the external wiring passes