Engine Coolant Bypass Valve A Stuck/Open
The coolant bypass valve A is stuck in the open position. Coolant always bypasses the radiator, leading to overheating under load.
Affected components
- Coolant bypass valve a
- Thermostat housing
Common causes
- High likelihood: Valve seized open by sediment or wax
- Medium likelihood: Broken return spring
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.