Cylinder 7 Glow Plug Control Circuit High
The P068D code indicates a high voltage condition in the glow plug control circuit for cylinder 7. This typically means the glow plug or its wiring has a short to power or an internal fault, causing excessive current draw. The glow plug control module monitors the circuit and sets this code when voltage is higher than expected. Common causes include a shorted glow plug, damaged wiring, or a faulty glow plug control module.
01. Most Common Causes
- Shorted glow plug in cylinder 7
- Damaged wiring or connector in the glow plug circuit
- Faulty glow plug control module
02. Symptoms You Will Notice
- Check Engine Light on
- Hard starting, especially in cold weather
- Rough idle or misfire on cylinder 7
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for other related codes.
Step 2: Visually inspect the glow plug wiring and connector for cylinder 7 for damage or corrosion.
Step 3: Measure resistance of the glow plug for cylinder 7; compare to specifications (typically 0.5-2 ohms).
Step 4: Check for voltage at the glow plug connector with key on; should be battery voltage during glow cycle.
Step 5: If wiring and plug are okay, test the glow plug control module output for cylinder 7.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances, as a shorted glow plug can damage the control module or cause a fire. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically $50-$150 for a glow plug replacement, plus diagnostic time. If the control module is faulty, costs can be higher.