Engine Coolant Bypass Valve D Range/Performance
The fourth coolant bypass valve responds to commands but the resulting coolant temperature behaviour is not as expected.
Affected components
- Coolant bypass valve d
- Thermostat housing
Common causes
- High likelihood: Valve partially stuck by sediment
- Medium likelihood: Weak return spring fails to close fully
- Low likelihood: Sensor element aged beyond calibration window
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.