What it means
The control line for the glow plug on cylinder 10 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 glow plug on cylinder 10 warms the combustion chamber for cold starts in a diesel engine. P069C sets when the control module detects abnormally low voltage in cylinder 10's glow plug control circuit, commonly because the wire is shorted to ground or the 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
- Record freeze-frame data and scan for other glow plug codes to check whether cylinder 10 is the only affected circuit.
- With the engine cool and ignition off, inspect cylinder 10's glow plug connector and control wire for chafing, corrosion, moisture, or a pushed-back pin.
- Compare cylinder 10 glow plug status or current with other cylinders during a cold start, if the scan tool provides that data.
- Disconnect the cylinder 10 glow plug following the vehicle wiring information and check whether the low circuit condition remains.
- Test the cylinder 10 plug and its isolated control wire for a short to ground, using the manufacturer's specification for comparison.
Common fixes
- Repair chafed cylinder 10 glow plug wiring or a damaged connector.
- Clean corrosion and restore a loose or pushed-back terminal at the cylinder 10 connector.
- Replace the cylinder 10 glow plug if testing confirms an internal short.
- Clear the code and verify cold-start operation after repair.
Can I keep driving?
In mild weather the engine may remain drivable, but cold starts can become difficult and produce white smoke during warm-up. Avoid repeated long cranking, which can drain the battery and strain the starter.
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.