What it means
The control module has detected an incorrect condition in the cylinder 9 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 glow plug in cylinder 9 supplies heat to help a diesel engine ignite fuel reliably when cold. The control module monitors the cylinder 9 glow plug circuit and sets this code when its electrical condition does not match what it expects; the code is not proof that the plug specification is wrong.
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 freeze-frame information and related codes first to determine the conditions when the cylinder 9 circuit fault was detected.
- Check the cylinder 9 glow plug connector and harness for corrosion, backed-out pins, damaged insulation, or poor routing near hot or moving parts.
- Measure the cylinder 9 plug's resistance or current draw and compare with the manufacturer's specification and other cylinders.
- Test the cylinder 9 wiring for continuity and shorts from the plug connector toward the glow-plug controller.
- If the plug and wiring pass, check the control circuit's cylinder 9 output using the vehicle's prescribed test method.
Common fixes
- Reseat and clean the cylinder 9 glow plug connector.
- Repair damaged or corroded wiring on the cylinder 9 branch.
- Replace the cylinder 9 glow plug if it fails the manufacturer's electrical check.
- Repair the control circuit if its cylinder 9 output or connection is faulty.
Can I keep driving?
You may be able to drive if the engine starts and runs smoothly, but cold starts may become unreliable and warm-up emissions can increase. Avoid repeated long cranking attempts if the engine will not start, and 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.