What does it mean?
C1216 is a Chassis (ABS, traction control, steering) fault code. It indicates: ABS Hydraulic Valve Power Relay Circuit Failure . 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 lamp that comes on and goes off again over several drives rather than staying on
- ABS and stability control dropping out and returning, often during cold starts
- Low system voltage recorded in the freeze frame data with the code
- Valve relay clicking more than once or sounding weak at key-on
- Occasional loss of ABS during heavy electrical load such as blower, lights and heated screen together
Likely causes
- Corroded or high resistance relay socket terminals causing a voltage drop when the valves draw current
- Relay contacts pitted or sticking, so the circuit switches slowly or erratically
- Weak battery or a charging fault leaving system voltage too low during cranking and heavy load
- Loose or corroded ABS ground point on the body or engine
- Relay coil resistance drifted out of specification with age and heat
- Loss of terminal tension in the ABS module connector, giving an intermittent connection
- Marginal internal driver in the ABS module
How to fix it
- Test the battery and charging system first, since low voltage sets this fault on an otherwise healthy circuit
- Perform voltage drop tests on the ABS power feed and ground while the system is commanded on
- Inspect and tension the relay socket and module connector terminals, and clean any oxide
- Substitute a known good relay of the correct part number and see if the fault stops recurring
- Monitor supply voltage on the scan tool while wiggling the harness and connectors
- Clean and retorque the ABS ground point on the chassis
- Repair the high resistance connection found; treat the module as the last candidate