Cylinder 5 Glow Plug Circuit Malfunction
The P06C9 code indicates that the glow plug for cylinder 5 is not operating within its expected parameters. This is typically caused by a faulty glow plug, an open or shorted circuit in the wiring, or a problem with the glow plug control module. The glow plug is essential for cold starts in diesel engines; when it fails, the cylinder may misfire or cause hard starting, especially in cold weather. The engine control module (ECM) monitors the resistance of each glow plug and sets this code when the reading for cylinder 5 is out of range.
01. Most Common Causes
- Faulty glow plug in cylinder 5
- Open or shorted wiring in the glow plug circuit
- Failed glow plug control module
- Corrosion or poor connection at the glow plug connector
02. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Rough idle or misfire on cylinder 5
- Check Engine Light illuminated
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan the vehicle for codes and record freeze frame data.
Step 2: Visually inspect the glow plug wiring and connector for cylinder 5 for damage or corrosion.
Step 3: Measure the resistance of the glow plug for cylinder 5; compare to manufacturer specs (typically 0.5-2 ohms).
Step 4: Check for voltage at the glow plug connector during the glow cycle (usually 12V).
Step 5: If wiring and voltage are OK, replace the glow plug for cylinder 5.
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 it may cause hard starting and poor performance. It's best to repair it promptly to avoid further issues.
How much does it cost to fix?▼
Typically between $50 and $150 for parts and labor, depending on the vehicle and accessibility of the glow plug.