P06C6
Cylinder 2 Glow Plug Incorrect.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 6
- AreaComputer and output circuits
- C6
- FaultThe specific fault in that area
What it means
P06C6 is a generic code meaning the engine or glow plug control unit has judged the cylinder 2 glow plug to be incorrect, so its electrical behaviour does not match what is expected. The control unit usually monitors the current drawn or the feedback from the glow plug circuit while it is switched on. The exact test and thresholds depend on the vehicle and the glow plug system fitted.
Symptoms
- Hard or slow starting on cold mornings
- Rough running or misfire on cylinder 2 when cold
- White or grey smoke from the exhaust after a cold start
- Glow plug warning light on, or the engine management light lit
- Increased cold-start noise (diesel knock)
Possible causes
- Faulty cylinder 2 glow plug (wrong resistance, open circuit or partial short)likely
- Corroded, loose or damaged connector or terminal at the cylinder 2 glow pluglikely
- Damaged wiring between the glow plug control module and cylinder 2, such as chafing, heat damage or high resistancepossible
- Poor power or earth supply to the glow plug system, such as a corroded feed or a weak batterypossible
- Faulty glow plug control module or output driver for cylinder 2possible
- Software or calibration fault in the control unit where the manufacturer has issued an update for this coderare
How to diagnose
- Read all stored codes and freeze frame data, noting the engine temperature and battery voltage when the fault set, and check for other glow plug codes on other cylinders.
- Check battery condition and charging voltage, as low voltage can upset glow plug monitoring.
- Visually inspect the cylinder 2 glow plug connector, terminal and wiring for corrosion, heat damage, chafing or water ingress.
- Check the glow plug system fuses and relays or power feed as described in the model-specific wiring information.
- Measure the cylinder 2 glow plug resistance or current draw and compare it with the other cylinders and the manufacturer's specification.
- Check the supply, earth and control signal at the glow plug or control module connector using the wiring diagram for the vehicle.
- If the plug and wiring are good, test the control module output for cylinder 2 and check for any applicable software updates for the vehicle.
How to fix
- Replace the cylinder 2 glow plug if it is out of specification, and consider replacing the set if the plugs are old, following the manufacturer's torque and procedure.
- Clean or repair the connector and terminals, or replace them if they are damaged.
- Repair or replace damaged wiring between the control module and the glow plug.
- Repair the power or earth supply fault, and replace or recharge a weak battery.
- Replace the glow plug control module if the cylinder 2 output is confirmed faulty.
- Apply a manufacturer calibration update only if one is known to address this code on the vehicle.
Can I keep driving?
Medium severity
The car can usually be driven short term, but starting will get harder and rougher in cold weather and the fault may spread to other glow plugs. Get it checked soon, and avoid repeated cold starts of a struggling engine.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.