Cylinder 3 glow plug ageing or failing, with resistance or current draw outside its range; Corroded, loose or damaged connector or terminal at the cylinder 3 glow plug; High resistance in the wiring or a poor earth or supply connection to the cylinder 3 circuit; Glow plug control module output stage fault for the cylinder 3 channel; Low or unstable battery or charging system voltage affecting the circuit readings; Fault in the engine control unit or glow plug module software or calibration, where a known update exists for the model.

P06BB

Cylinder 3 Glow Plug Circuit Range/Performance.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
6: AreaComputer and output circuits
BB: FaultThe specific fault in that area

What it means

P06BB is the generic code for a range or performance fault in the glow plug circuit for cylinder 3 on a diesel engine. The engine control unit or glow plug control module monitors the current drawn or the circuit feedback for that plug, and it saw a value outside the expected window. The circuit is not necessarily open or shorted, so the plug may be weak, high in resistance or only partly working.

Symptoms

Hard starting or extended cranking on cold mornings
White or grey smoke and rough running just after a cold start
Glow plug warning light on, flashing or staying lit
Engine management light on
Noticeable misfire or uneven idle on cylinder 3 until warm
Slightly higher emissions or fuel use when cold

Possible causes

Cylinder 3 glow plug ageing or failing, with resistance or current draw outside its rangelikely
Corroded, loose or damaged connector or terminal at the cylinder 3 glow pluglikely
High resistance in the wiring or a poor earth or supply connection to the cylinder 3 circuitpossible
Glow plug control module output stage fault for the cylinder 3 channelpossible
Low or unstable battery or charging system voltage affecting the circuit readingspossible
Fault in the engine control unit or glow plug module software or calibration, where a known update exists for the modelrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting engine temperature and battery voltage when the fault set, and check for other glow plug codes
Check the battery condition and charging voltage, as low voltage can upset glow plug circuit monitoring
Visually inspect the glow plug wiring, connector and terminal for cylinder 3 for corrosion, heat damage, chafing or looseness
Check the glow plug control module connectors, supply fuses and earth connections
Measure the resistance of the cylinder 3 glow plug and compare it with the other plugs and the manufacturer's specification
Use a scan tool to view glow plug live data or run the glow plug output test, if the model supports it, and compare cylinder 3 with the others
Check the supply, earth and voltage drop on the cylinder 3 circuit while it is energised
Check for any manufacturer software updates or technical bulletins for the engine concerned, as procedures vary by model

How to fix

Replace the cylinder 3 glow plug, and consider replacing the set if they are old, using the correct torque and following the manufacturer's procedure
Clean or repair the connector and terminals, or replace them if they are damaged
Repair high-resistance wiring or poor supply and earth connections
Replace the glow plug control module if its cylinder 3 output is proven faulty
Correct battery or charging faults, then clear the codes and retest
Apply a manufacturer software update only where an outdated calibration is a known cause for that model

Can I keep driving?

Low severity

The car can normally be driven, but cold starting may be poor and a seized glow plug can be difficult to remove later. Book it in soon, especially before cold weather.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.