What it means
The control line for the glow plug on cylinder 8 is shorted to ground or the plug is internally shorted.
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 for the cylinder 8 glow plug while it commands preheating. This code sets when the circuit voltage is lower than expected, such as when the cylinder 8 control wire is grounded or the glow plug is internally shorted.
Common causes
Most likely first.
- Control line shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
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
- Use a scan tool to record freeze-frame data and check glow-plug status or control data, if available, to see when the cylinder 8 fault occurs.
- With the engine cool and ignition off, inspect the cylinder 8 glow-plug connector and nearby harness for corrosion, loose pins, or insulation rubbed through to ground.
- Compare the cylinder 8 circuit with the other glow-plug circuits using the vehicle wiring information to identify an unusual connection or damage.
- Check the cylinder 8 control wire for an unintended path to ground, following the manufacturer's circuit test procedure.
- Test the cylinder 8 glow plug and its wiring for an internal short or continuity fault according to the manufacturer's specification.
Common fixes
- Clean and secure corroded or loose cylinder 8 connector pins.
- Repair chafed cylinder 8 control-wire insulation and restore proper routing.
- Repair a control wire that is shorted to ground.
- Replace the cylinder 8 glow plug if it fails the specified test.
Can I keep driving?
If the engine starts and runs normally, a short trip may be possible, but avoid relying on the vehicle for cold starts. In cold weather, hard starting, misfiring during warm-up, or white smoke may worsen.
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.