Cylinder 10 Glow Plug Control Circuit Low
The P069C code indicates that the powertrain control module (PCM) has detected a low voltage condition in the glow plug control circuit for cylinder 10. This circuit supplies power to the glow plug, which preheats the combustion chamber for cold starts in diesel engines. A low voltage reading suggests excessive resistance, a short to ground, or a faulty glow plug or relay, potentially causing hard starting and increased emissions.
01. Most Common Causes
- Faulty glow plug in cylinder 10
- Open or shorted glow plug wiring or connector
- Failed glow plug relay or fuse
- Corrosion or damage in the glow plug control module
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Hard starting, especially in cold weather
- Rough idle or misfire on cylinder 10
- Increased exhaust smoke during startup
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data to confirm P069C.
Step 2: Visually inspect glow plug wiring and connector for cylinder 10 for damage, corrosion, or loose connections.
Step 3: Measure resistance of glow plug 10; compare to spec (typically 0.5-2 ohms). High resistance indicates a bad plug.
Step 4: Check voltage at glow plug connector with key on; should be battery voltage. If low, test relay and fuse.
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 cranking, battery drain, or unburned fuel damage. It's best to repair promptly.
How much does it cost to fix?▼
Typically $50-$150 for a single glow plug replacement, including parts and labor. If wiring or relay issues are found, costs may be higher.