Faulty glow plug on cylinder 7 (open or shorted element); Damaged or corroded electrical connector at the glow plug; Chafed or broken wire in the glow plug circuit; Failed glow plug control module or relay; Poor ground connection for the glow plug circuit; Engine control module software issue or internal fault (less common)

DTC codes / P06xx · Computer and output circuits / P06BF

P06BFCylinder 7 Glow Plug Circuit Range/Performance

Q: What does code P06BF mean?

Cylinder 7 Glow Plug Circuit Range/Performance. P06BF indicates that the engine control module has detected a range or performance fault in the glow plug circuit for cylinder 7, typically on diesel engines. The module monitors the circuit's electrical behavior and flags an issue when the current or voltage falls outside the expected range during glow plug activation.

P06BF indicates that the engine control module has detected a range or performance fault in the glow plug circuit for cylinder 7, typically on diesel engines. The module monitors the circuit's electrical behavior and flags an issue when the current or voltage falls outside the expected range during glow plug activation.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Hard starting or rough idle when the engine is cold
Excessive white smoke from the exhaust after a cold start
Misfire or stumbling during the first few minutes of operation
Reduced fuel economy during warm-up
In rare cases, a no-start condition in very cold weather

Common causes, most likely first

Faulty glow plug on cylinder 7 (open or shorted element)
Damaged or corroded electrical connector at the glow plug
Chafed or broken wire in the glow plug circuit
Failed glow plug control module or relay
Poor ground connection for the glow plug circuit
Engine control module software issue or internal fault (less common)

How to diagnose and fix it

Scan all modules for stored codes and freeze-frame data to confirm P06BF is current
Visually inspect the cylinder 7 glow plug, connector, and wiring for damage or corrosion
Measure glow plug resistance with a multimeter and compare to the manufacturer's specification
Check for voltage and ground at the glow plug connector during the glow plug activation period
Test the glow plug control module and its wiring if the plug and circuit test good
Replace the faulty glow plug or repair damaged wiring as needed
Clear codes and verify the repair with a road test or glow plug activation test

Glow Plug Circuit Checks That Prevent Misdiagnosis

A glow plug that tests good on resistance can still cause P06BF if the control module's current monitoring circuit is faulty, so always verify control side operation.
Corroded terminals at the glow plug are a frequent cause that is often overlooked because the plug itself tests fine.
P06BF can be set by a weak battery or poor ground that causes low voltage during glow plug activation, mimicking a failed plug.
On some vehicles, the glow plug control module is integrated into the engine control module, making diagnosis more involved and expensive.
Do not replace all glow plugs just because one code is set; address only the affected cylinder unless the others test out of specification.

Can I keep driving with P06BF?

You can generally continue driving, but cold starting and warm-up performance may be affected, and prolonged driving with a faulty glow plug can lead to carbon buildup or further electrical damage. Avoid heavy loads or high speeds until the fault is repaired, especially in cold weather.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.