P067B
Cylinder 4 Glow Plug Control Circuit High
Diesel glow plug / preheat
Generic OBD-II
High
What it means
P067B is a diesel-engine code showing a high-voltage (open or short-to-power) fault in the control circuit for the cylinder 4 glow plug. Glow plugs preheat the cylinders for easy cold starting, so this fault typically shows up as hard cold starts and rough running until the engine warms. The engine still runs, but the cylinder 4 glow plug circuit needs repair.
High
Can I keep driving? The engine still runs, but on a diesel it may be hard to start and run rough when cold until the cylinder 4 glow plug circuit is repaired.
Common symptoms
What you'll notice
- Hard starting, especially in cold weather
- Check-engine (or glow plug) light on
- Rough running and shudder when the engine is cold
- White or grey smoke from the exhaust on a cold start
Common causes
Most likely first
- Open or short-to-voltage in the cylinder 4 glow plug control circuitLikely
- Failed glow plug on cylinder 4Common
- Corroded or loose connector at the glow plugCommon
- Glow plug control module fault driving the cylinder 4 output highLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check for glow plug codes on other cylinders.
- Inspect the wiring and connector to the cylinder 4 glow plug for opens or shorts to voltage.
- Measure the resistance of the cylinder 4 glow plug and compare to the others.
- Repair the control circuit or replace the glow plug, then clear and re-test on a cold start.
FAQ
Quick answers
Is it safe to drive with P067B?+
Yes once running, but cold starts get harder and the engine runs rough until warm, so repair it soon.
Can I just clear P067B?+
It will return until the cylinder 4 glow plug control circuit fault is repaired.
Related codes
Often seen with P067B
Read & clear P067B yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX