What it means
The control module has detected an incorrect condition in the cylinder 1 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 1 glow plug warms the combustion chamber to assist a diesel engine during cold starts. The control module monitors the cylinder 1 circuit response and sets this code when it detects an out-of-range or otherwise incorrect electrical condition; the code alone does not prove that the plug type 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 and glow plug live data to establish when the cylinder 1 fault occurs and compare its response with other cylinders.
- Inspect the cylinder 1 glow plug, connector, and nearby wiring for corrosion, loose terminals, heat damage, or chafing.
- Test the cylinder 1 glow plug using the manufacturer's procedure and check the result against the manufacturer's specification.
- Verify the fitted plug is the specified type for the vehicle, then test cylinder 1 circuit wiring and connections using the wiring diagram.
- If the plug and harness are correct, test the glow plug controller's cylinder 1 output and control circuit.
Common fixes
- Clean and secure the cylinder 1 glow plug connector.
- Repair damaged or corroded wiring in the cylinder 1 circuit.
- Replace a failed cylinder 1 glow plug with the specified type.
- Repair the controller or cylinder 1 control circuit if testing confirms an electrical fault.
Can I keep driving?
If the engine starts and runs normally, driving may be possible, but cold starting can become difficult and white smoke during warm-up may increase. Avoid repeated cranking if it will not start, and repair 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.