The P0674 trouble code indicates an issue with the glow plug circuit for cylinder 4 in a diesel engine. Glow plugs are essential components used to preheat the combustion chamber for easier cold starts in diesel engines. When the powertrain control module (PCM) detects a fault in the glow plug circuit for cylinder 4, it triggers the P0674 code.
Glow Plug Cylinder 4 Circuit
Code symptoms P0674.
1. Check Engine Light (CEL) illuminated on the dashboard.
2. Difficulty starting the engine, particularly in cold weather.
3. Rough idle or misfiring during cold starts.
4. Decreased engine performance and fuel efficiency, especially during cold starts.
5. Other related trouble codes may be present, depending on the specific issue.
This code is common in brands such as:: Chevrolet, Renault, Ford, Toyota, Nissan, Mercedes Benz, Honda.
Causes of the code P0674.
1. Faulty glow plug in cylinder 4.
2. Wiring or connector issues in the glow plug circuit for cylinder 4, such as corrosion, damaged wires, or loose connections.
3. Faulty glow plug relay or module.
4. Failed engine control module (ECM) or powertrain control module (PCM).
Code Solutions P0674.
1. Use a diagnostic scanner to retrieve freeze frame data and all associated trouble codes. This information can help pinpoint the root cause of the issue.
2. Inspect the glow plug in cylinder 4 for any signs of damage or wear. Test the glow plug using a digital multimeter to ensure it is within the specified resistance range. Replace the glow plug if it is found to be faulty.
3. Inspect the wiring and connectors related to the glow plug circuit for cylinder 4 for any signs of damage, corrosion, or loose connections. Repair or replace damaged components as needed.
4. Test the glow plug relay or module using a scan tool capable of bi-directional control to ensure it is functioning properly. Replace the relay or module if it is found to be faulty.
5. If the wiring, connectors, and glow plug are in good condition but the code persists, it may indicate a fault in the ECM or PCM. In this case, the module may need to be replaced or reprogrammed by a qualified technician.
6. After any repairs are made, clear the trouble codes and perform a test drive to verify that the issue has been resolved. If the code returns, further diagnosis may be necessary to identify the underlying problem.
7. Follow manufacturer-specific diagnostic procedures outlined in the vehicle’s service manual to accurately diagnose and repair issues related to the glow plug circuit for cylinder 4. If needed, seek assistance from a qualified technician or dealership.