What it means
The cylinder 12 glow plug control circuit voltage is below the expected range. The cause may be the plug, its wiring or connections, or the control circuit.
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 12 glow plug during diesel preheating. P06E2 sets when voltage in that specific circuit is below the expected range, often because the control wire is shorted to ground or a connector has excessive resistance.
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 faults to see whether the problem is isolated to cylinder 12.
- Use the vehicle's cylinder layout to locate cylinder 12, then inspect its glow plug lead for chafing, exposed conductors, or heat damage.
- Inspect the cylinder 12 connector for corrosion, poor pin contact, or a terminal pushed back into the housing.
- Test the cylinder 12 control wire for a short to ground and check its continuity using the manufacturer's diagnostic procedure.
- If the harness and connector pass, test the cylinder 12 glow plug and control output to the manufacturer's specification.
Common fixes
- Clean and reseat the cylinder 12 glow plug connector.
- Repair a chafed or grounded cylinder 12 control wire.
- Repair corroded, loose, or pushed-back terminals in the cylinder 12 circuit.
- Replace the cylinder 12 glow plug or repair its control circuit if testing confirms a failure.
Can I keep driving?
The engine may be harder to start when cold and may emit white smoke during warm-up; avoid relying on it in cold conditions until the cylinder 12 circuit is checked. If the engine runs roughly after starting, limit driving until the fault 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.