P06BF

What it means

P06BF is a generic code meaning the glow plug circuit for cylinder 7 is operating outside its expected range or performance. The glow plug control module or engine control unit monitors the current draw, resistance or feedback of each glow plug, and it saw a value for cylinder 7 that did not match what it expected. The fault is in the circuit's electrical behaviour rather than a plain open or short circuit. How the cylinder is numbered and how the glow plugs are driven depends on the engine, so check the model-specific information.

Symptoms

• Hard or slow starting on cold mornings, with more cranking needed
• White or grey smoke and rough running just after a cold start
• Engine management or glow plug warning light on
• Misfire or uneven idle on cold start that clears as the engine warms
• Increased cold-start emissions or diesel knock when cold
• No noticeable symptoms when warm, with only a stored code

Possible causes

• Cylinder 7 glow plug ageing or degraded, with resistance or current draw out of rangelikely
• Corroded, loose or damaged glow plug connector or terminal on cylinder 7, giving high resistancelikely
• Wiring fault between the glow plug and the control module, such as chafed or high-resistance wiring or a poor earthpossible
• Low battery voltage or a weak charging system affecting glow plug current and its monitoringpossible
• Glow plug control module output stage fault or internal failure for that channelpossible
• Outdated control unit software that mis-evaluates glow plug feedback, where the manufacturer has a known updaterare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting coolant temperature and battery voltage when the code set, and check for other glow plug codes on different cylinders.
2. Check battery condition and charging voltage, as low voltage can upset glow plug readings.
3. Visually inspect the cylinder 7 glow plug connector and wiring for corrosion, heat damage, chafing, water ingress and a secure fit.
4. Check the glow plug control module connector, power feeds, fuses and earth connections for voltage drop under load.
5. Measure the cylinder 7 glow plug resistance with the harness disconnected and compare it with the others and the manufacturer specification.
6. With a suitable meter or clamp, check the current drawn by the cylinder 7 plug during a cold-start heating cycle and compare it with the other cylinders.
7. Use live data or an actuator test, if the vehicle supports it, to see the glow plug commanded state and feedback for cylinder 7.
8. Check for a software update or technical service bulletin for your model and engine if the plug and wiring test fine.

How to fix

• Replace the cylinder 7 glow plug if its resistance or current is out of specification, and consider replacing the set if they are all of similar age and condition.
• Clean or replace the corroded or damaged connector and terminal, and secure the connection.
• Repair or replace the damaged wiring or poor earth between the module and the glow plug.
• Restore battery and charging system health if voltage is low.
• Replace the glow plug control module if its output for cylinder 7 is faulty, and follow any coding procedure the manufacturer requires.
• Apply a manufacturer software update only where an outdated calibration is a known cause for your model.

Can I keep driving?

Nearby codes

• P06BEGenericCylinder 6 Glow Plug Circuit Range/Performance
• P06C0GenericCylinder 8 Glow Plug Circuit Range/Performance