What this code means

The PCM has detected that the fuel system failed to transition from open loop to closed loop operation within the expected time. This indicates the engine is running in open loop longer than normal, which reduces fuel efficiency and increases emissions.

Symptoms

• Check Engine Light
• Poor fuel economy
• Higher emissions output
• Rough idle when cold

Common causes

• Faulty oxygen sensor not reaching operating temperature
• Engine coolant temperature sensor malfunction
• Exhaust leak before oxygen sensor
• Fuel pressure out of specification
• Vacuum leak preventing closed loop entry

Diagnostic steps

1. Monitor O2 sensor activity on scan tool to verify switching
2. Check engine coolant temperature sensor reading vs actual temp
3. Inspect exhaust for leaks near O2 sensor
4. Verify fuel pressure is within specification
5. Check for vacuum leaks

Repair notes

Diagnose and repair the condition preventing closed loop operation, typically an O2 sensor or coolant temp sensor issue.

Other Powertrain codes on this vehicle