Engine Coolant Bypass Valve D Stuck Closed
The fourth coolant bypass valve is stuck closed.
Affected components
- Coolant bypass valve d
- Thermostat housing
Common causes
- High likelihood: Valve seized closed by debris
- Medium likelihood: Actuator linkage jammed in closed position
- Low likelihood: Carbon or debris buildup preventing free movement
Diagnostic notes
- The malfunction indicator lamp may illuminate
Related codes
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.