What it means
The control line for the glow plug on cylinder 8 is open or shorted to supply - the plug cannot be heated.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The engine controller monitors the control circuit that heats the cylinder 8 glow plug during preheating. This code sets when the circuit voltage is higher than expected, which can happen if the plug or wiring is open or the control wire is shorted to supply voltage.
Common causes
Most likely first.
- Open in plug or wiring
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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
- Record freeze-frame data and check available glow-plug command or status data to confirm the fault is associated with cylinder 8.
- With ignition off and the engine cool, inspect the cylinder 8 glow-plug connector and harness for disconnected pins, corrosion, pinched wiring, or damage near power feeds.
- Use the vehicle wiring information to trace the cylinder 8 control circuit and check for an open or an unintended connection to supply.
- Check continuity through the cylinder 8 control wire and connector terminals using the manufacturer's procedure.
- Test the cylinder 8 glow plug against the manufacturer's specification to distinguish a failed plug from a wiring fault.
Common fixes
- Reconnect or secure a loose cylinder 8 glow-plug connector.
- Clean corroded connector pins and repair poor terminal contact.
- Repair an open or pinched cylinder 8 control wire.
- Repair wiring that is shorted to supply voltage.
- Replace the cylinder 8 glow plug if it fails the specified test.
Can I keep driving?
The vehicle may run normally once started, but cold starts can become difficult and warm-up emissions may rise. Avoid depending on it in cold conditions until the cylinder 8 glow-plug circuit is repaired.
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.