Cathode Bypass Valve Control Circuit
Generic electrical fault on the cathode bypass valve control. Bypass routes air around the stack during startup or low-load operation.
Affected components
- Cathode bypass valve
- Valve wiring
Common causes
- High likelihood: Valve actuator failed
- Low likelihood: Gateway module routing CAN messages incorrectly
- Low likelihood: CAN terminating resistor (120 Ω) drifted out of spec
Possible symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Diagnostic notes
- The malfunction indicator lamp may illuminate
- A drive cycle may be required after repair
- Reduced-power or limp mode may occur
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.