Cylinder 4 Glow Plug Control Circuit Low
The P067A code indicates that the powertrain control module (PCM) has detected a low voltage condition in the glow plug control circuit for cylinder 4. This typically means the glow plug or its wiring has excessive resistance or a short to ground, preventing proper heating during cold starts. In diesel engines, glow plugs are essential for ignition in cold weather; a fault can cause hard starting, misfires, and increased emissions.
1. Most Common Causes
- Faulty glow plug in cylinder 4
- Open or shorted wiring in the glow plug circuit
- Corroded or loose connector at the glow plug
- Failed glow plug control module or relay
2. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Engine misfire or rough idle on cold start
- Check Engine Light illuminated
- Reduced fuel economy
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the glow plug wiring and connector at cylinder 4 for damage or corrosion.
Step 3: Measure resistance of glow plug 4; compare to specification (typically 0.5-2 ohms).
Step 4: Check voltage at the glow plug connector during glow plug activation (should be battery voltage).
Step 5: Test the glow plug control module/relay for proper output.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code, especially in cold weather, as it can cause hard starting, misfires, and potential damage to the engine or catalytic converter.
How much does it cost to fix?▼
The cost to fix P067A typically ranges from $50 to $150 for a DIY glow plug replacement, or $150 to $400 if professional labor is required, depending on vehicle make and model.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.