P0675

What P0675 Means

Code P0675 points to a fault in the glow plug circuit for cylinder 5. The engine management system (DME) detects a deviation in the glow plug electrical circuit, which can be caused by a failed glow plug, wiring problems, or a faulty glow plug control module.

Glow plugs heat the combustion chamber of a diesel engine before startup, especially at low temperatures. The Glow Plug Control Module regulates voltage to the glow plugs based on engine temperature and operating conditions. When a fault occurs in the cylinder 5 circuit, the DME sets code P0675 and may limit glow plug system operation.

Symptoms

• Check Engine light: the malfunction indicator lamp comes on in the instrument cluster.
• Hard cold starting: the engine may crank longer or start with difficulty at low temperatures.
• Rough cold idle: after a cold start, you may notice stumbling, vibration, or uneven running.
• Higher emissions: incomplete combustion in cold mode can raise emission levels.

Diagnosis and Repair

Step 1: Check the Glow Plug

• Remove the cylinder 5 glow plug and inspect it for wear, carbon buildup, or mechanical damage.
• Check glow plug resistance with a multimeter; replace the plug if it's out of spec.

Step 2: Check the Wiring and Connector

• Inspect the wiring harness and connector leading to the cylinder 5 glow plug for opens, corrosion, or damage.
• Make sure the connection is secure and free of corrosion.

Step 3: Check the Glow Plug Control Module

• If one or more glow plugs are good but the code persists, check the Glow Plug Control Module.
• Multiple glow plug failures point to a faulty control module.

Step 4: Replace Faulty Components

• Replace the faulty glow plug, damaged wiring, or control module based on your diagnosis.
• After the repair, clear the fault code and take a test drive to verify.

Secondary Problems

Ignoring code P0675 can lead to the following:

• Hard starting and added engine wear: a dead glow plug makes cold starts worse, which puts more load on the starter motor and battery.
• Carbon and deposit buildup: incomplete combustion in the cold cylinder promotes carbon buildup on the valves and piston, which reduces engine efficiency over time.
• Higher emissions and catalytic converter risk: unburned fuel can reach the exhaust system and speed up catalytic converter degradation.
• Cascading faults: the failure can trigger additional codes related to engine operation and the exhaust system.

Fix the fault at the first opportunity, especially before the cold season.