Cylinder 4 Glow Plug Control Circuit High
The P067B code indicates that the powertrain control module (PCM) has detected a high voltage condition in the glow plug control circuit for cylinder 4. This typically means the circuit resistance is too low or there is a short to voltage, preventing proper glow plug operation. Common causes include a faulty glow plug, damaged wiring or connector, or a defective glow plug control module. This code is specific to diesel engines and can lead to hard starting, misfires, and increased emissions.
01. Most Common Causes
- Faulty glow plug in cylinder 4
- Short to voltage in glow plug wiring or connector
- Damaged glow plug control module or relay
02. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Engine misfire or rough idle
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for additional codes.
Step 2: Visually inspect the glow plug wiring and connector for cylinder 4 for damage, corrosion, or shorts.
Step 3: Measure resistance of the glow plug for cylinder 4; compare to specifications (typically 0.5-2 ohms).
Step 4: Check for voltage at the glow plug connector with the ignition on; if voltage is present when it shouldn't be, trace the short.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code, as it can cause hard starting, poor engine performance, and potential damage to the glow plug system or PCM.
How much does it cost to fix?▼
The cost to fix P067B typically ranges from $50 to $150 for parts and labor, depending on whether a glow plug or wiring repair is needed.