P06C8

Cylinder 4 Glow Plug Incorrect

Q: Is it safe to drive with P06C8?

Generally yes, but cold starts will be harder and the engine may run rough and smoky when cold until the plug is corrected.

Q: Can I just clear P06C8?

It will return when the module re-checks the plug. If the wrong glow plug was fitted, it needs to be swapped for the correct part.

Glow plug / diesel preheat Generic OBD-II High

What it means

P06C8 is a diesel code meaning the control module measured the cylinder 4 glow plug and found its electrical characteristics don't match what it expects — commonly a wrong or non-spec plug fitted, or one whose resistance has drifted out of range. Glow plugs preheat the cylinder for starting, so the main effects are hard cold starts and rough, smoky running until the engine warms.

High

Can I keep driving? Usually drivable — expect hard cold starts and rough, smoky running until warm; a single mismatched glow plug rarely stops the engine from starting.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Hard starting when the engine is cold
Rough running or misfire until the engine warms up
White or grey exhaust smoke on cold starts
Check-engine or glow-plug warning light on

Common causes

Most likely first

Wrong-specification glow plug fitted to cylinder 4Likely
Faulty cylinder 4 glow plug (out-of-range resistance)Common
Wiring or connector fault at the cylinder 4 glow plugCommon
Faulty glow plug control moduleLess often

How to diagnose & fix

Work through it in order

Confirm the correct glow plug part number for the engine and check that cylinder 4 has the right plug fitted.
Measure the cylinder 4 glow plug's resistance and compare it to the others.
Replace the plug with the correct-spec part if it is wrong or out of range.
Inspect the wiring and connector, and test the control module output if needed. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P06C8?+

Generally yes, but cold starts will be harder and the engine may run rough and smoky when cold until the plug is corrected.

Can I just clear P06C8?+

It will return when the module re-checks the plug. If the wrong glow plug was fitted, it needs to be swapped for the correct part.

Read & clear P06C8 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX