Cylinder 11 Glow Plug Circuit Malfunction
The P0681 code indicates a fault in the glow plug circuit for cylinder 11, typically found in diesel engines. The glow plug system preheats the combustion chamber for cold starts. This code is set when the Engine Control Module (ECM) detects an open or short circuit in the glow plug or its wiring, or a glow plug that draws incorrect current. This can lead to hard starting, especially in cold weather, and increased emissions.
01. Most Common Causes
- Faulty glow plug in cylinder 11
- Open or shorted wiring in the glow plug circuit
- Failed glow plug relay or fuse
- Corroded or loose connector at the glow plug
- ECM issue (rare)
02. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Check Engine Light illuminated
- Rough idle or misfire on cold start
- Excessive smoke on startup
03. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0681 is present. Check for other related codes.
Step 2: Visually inspect the glow plug wiring and connector for cylinder 11 for damage, corrosion, or loose connections.
Step 3: Test the glow plug resistance using a multimeter (should be low ohms, typically 0.5-2 ohms). Compare with other cylinders.
Step 4: Check voltage at the glow plug connector with the key on/engine off (should be battery voltage). If no voltage, test the relay and fuse.
Step 5: If wiring and voltage are OK, replace the glow plug for cylinder 11.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances in mild weather, but cold starts will be difficult and may cause excessive smoke. Prolonged driving with a faulty glow plug can lead to incomplete combustion, increased emissions, and potential damage to the catalytic converter. It's best to repair promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a single glow plug replacement, including parts and labor. If wiring or relay issues are found, costs may be higher. Diagnostic fees may apply.