What it means
The cylinder 8 glow plug circuit is not performing within the expected range. The cause may be the glow plug, its wiring or connections, or the control circuit.
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 that cylinder to help a diesel engine start and run cleanly when cold. The control module monitors the cylinder 8 glow plug circuit’s electrical response and sets this code when its performance falls outside the expected range.
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
- Read the freeze-frame data and glow plug live data to see whether the fault occurred during a cold start and whether cylinder 8 differs from the others.
- With the engine off, inspect the cylinder 8 glow plug connector and nearby wiring for looseness, corrosion, heat damage, or chafing.
- Check the cylinder 8 glow plug’s electrical condition using the manufacturer's procedure and compare it with the manufacturer's specification.
- Test the cylinder 8 circuit wiring and connections for continuity and unwanted resistance, following the wiring diagram.
- If the plug and wiring pass, test the glow plug control circuit and module output according to the manufacturer's procedure.
Common fixes
- Clean and secure the cylinder 8 glow plug connector.
- Repair damaged or corroded cylinder 8 circuit wiring.
- Replace the cylinder 8 glow plug if it fails the specified test.
- Repair or replace the glow plug control circuit component if testing identifies a fault.
Can I keep driving?
If the engine starts and runs normally, short trips may be possible, but cold starts can become difficult and warm-up emissions may rise. Avoid repeated cranking if it will not start, since this can drain the battery; address the fault before relying on the vehicle in cold conditions.
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.