P068F
Cylinder 8 Glow Plug Control Circuit High
Glow plugs (diesel)
Generic OBD-II
High
What it means
P068F is a diesel code meaning the control circuit for the cylinder-8 glow plug is reading high — typically an open or high resistance in that plug's circuit. Glow plugs pre-heat each cylinder for cold starting, so a faulty one on cylinder 8 makes cold starts harder and smokier. It points at that specific glow plug or its wiring rather than the whole engine.
High
Can I keep driving? The engine usually still runs, but the cylinder-8 glow plug is not being controlled properly, so cold starts can be harder and smokier until it is fixed.
Common symptoms
What you'll notice
- Check-engine light on (often with a glow-plug warning light)
- Harder starting when cold
- Rough running or a slight miss until the engine warms up
- White exhaust smoke on a cold start
Common causes
Most likely first
- Faulty cylinder-8 glow plug (open or high resistance)Likely
- Open in the glow-plug control wire or a broken connectorCommon
- Corroded or loose connector at the cylinder-8 glow plugCommon
- Faulty glow plug control moduleLess often
How to diagnose & fix
Work through it in order
- Scan and read freeze-frame data to confirm the fault is on the cylinder-8 glow-plug control circuit.
- Locate the cylinder-8 glow plug and inspect its connector and wiring for an open, chafing, or a loose pin.
- Measure the glow plug's resistance and compare it to the others; replace it if it reads open or out of spec.
- If the plug and wiring are good, test the glow plug control module output for that cylinder and replace the module if it is at fault.
FAQ
Quick answers
Is it safe to drive with P068F?+
Usually yes once running, but one dead glow plug makes cold starts harder and dirtier. Repair it before cold weather.
Can I just clear P068F?+
It clears, but returns once the circuit faults again. The cylinder-8 glow plug or its wiring needs to be checked.
Related codes
Often seen with P068F
Read & clear P068F 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