Cylinder 8 Glow Plug Control Circuit Low
The P068E code indicates that the powertrain control module (PCM) has detected a low voltage condition in the glow plug control circuit for cylinder 8. This circuit includes the glow plug, wiring, connector, and the glow plug control module. A low voltage reading suggests excessive resistance, a short to ground, or a failed component, preventing the glow plug from heating properly for cold starts.
01. Most Common Causes
- Faulty glow plug in cylinder 8
- Open or shorted wiring in the glow plug circuit
- Corroded or damaged connector at the glow plug
- Failed glow plug control module
02. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Check Engine Light illuminated
- Rough idle or misfire on cylinder 8
- Excessive white smoke from exhaust on startup
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the glow plug wiring and connector for cylinder 8 for damage or corrosion.
Step 3: Measure resistance of the glow plug; should be low (0.5-2 ohms). High resistance indicates a bad glow plug.
Step 4: Check voltage at the glow plug connector with the key on; should be battery voltage. If low, test the control module and wiring.
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 misfire can damage the catalytic converter.
How much does it cost to fix?▼
Typically $50-$150 for a DIY glow plug replacement. If the control module or wiring needs repair, costs can be higher.