What it means
The control module has detected an incorrect condition in the cylinder 8 glow plug circuit. The code does not by itself establish that the wrong plug type was fitted.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The cylinder 8 glow plug warms the air in its combustion chamber so a diesel engine can start more readily and burn fuel cleanly when cold. The control module monitors the cylinder 8 plug circuit and stores this code when the circuit response is incorrect; it does not establish that an incorrect plug type was installed.
Common causes
Most likely first.
- Faulty glow plug
- Damaged or corroded wiring or connector
- Glow plug control circuit fault
Symptoms
- Glow plug warning light on (often orange coil symbol)
- Hard cold start or no start in cold weather
- White smoke from exhaust during warm-up
How to diagnose it
- Capture freeze-frame data and check for other glow-plug codes to establish whether the cylinder 8 fault occurred during a cold start or with a shared control problem.
- Inspect the cylinder 8 plug terminal and its wiring for corrosion, looseness, insulation damage, or signs of overheating.
- Test the cylinder 8 glow plug's resistance or current draw against the manufacturer's specification and compare it with other cylinders.
- Use the wiring diagram to check continuity and shorts in the cylinder 8 branch between the plug and the glow-plug control circuit.
- If the plug and branch wiring are sound, test the control circuit output as directed by the manufacturer.
Common fixes
- Clean and secure the cylinder 8 glow plug connection.
- Repair an open, chafed, or corroded section of cylinder 8 wiring.
- Replace the cylinder 8 glow plug if its electrical test is outside specification.
- Repair the glow-plug control circuit if the output test points to a circuit fault.
Can I keep driving?
If it runs normally, limited driving is generally possible, but expect harder cold starts and potentially more white smoke during warm-up. Do not keep cranking a reluctant engine for long periods, since that can drain the battery and strain the starter.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.