Cylinder 4 Glow Plug Incorrect
The P06C8 code indicates that the Engine Control Module (ECM) has detected a fault with the glow plug in cylinder 4, typically due to incorrect resistance or an open/short circuit. This affects cold start performance and emissions, and may trigger the check engine light.
1. Most Common Causes
- Faulty glow plug in cylinder 4
- Open or short circuit in glow plug wiring
- Failed glow plug relay or control module
- Corrosion or poor connection at the glow plug connector
2. Symptoms You Will Notice
- Check engine light illuminated
- Hard starting, especially in cold weather
- Rough idle or misfire on cylinder 4
- Excessive smoke on startup
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm code P06C8 and check for related codes.
Step 2: Visually inspect the glow plug connector and wiring for damage or corrosion.
Step 3: Measure resistance of cylinder 4 glow plug; compare to manufacturer specs (typically 0.5-2 ohms).
Step 4: Test glow plug relay and control circuit for proper voltage and ground.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but starting may be difficult in cold weather and the engine may run rough. Prolonged driving can cause misfire and catalytic converter damage.
How much does it cost to fix?▼
Replacing a single glow plug costs $50-$150 including parts and labor. If the relay or wiring is faulty, costs may be higher.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.