Engine Coolant Bypass Valve A Position Sensor Circuit Intermittent/Erratic
The bypass valve A position sensor signal jumps or drops out intermittently. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Affected components
- Bypass position sensor a
- Wiring harness
Common causes
- High likelihood: Sensor connector not fully seated
- Medium likelihood: Harness chafed near thermostat housing
- Low likelihood: Connector with intermittent contact under vibration
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.