Damaged, chafed or shorted wiring on the control circuit between the ECU and glow plug control module 2, including a short to voltage; Corroded, loose or damaged connector terminals at the control module or ECU; Faulty glow plug control module 2 with an internal fault in its control input or driver; Poor power or earth supply to the module causing an incorrect signal state; Water ingress or heat damage affecting the module or its wiring; Fault inside the engine ECU control output; Outdated ECU software where the manufacturer has issued a known fix for the model.

P06F8

Glow Plug Control Module 2 Control Circuit High.

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
F8: FaultThe specific fault in that area

What it means

P06F8 is a generic code meaning the engine control unit has detected a high voltage or high-signal fault on the control circuit for glow plug control module 2. The ECU commands the module and monitors the circuit, and it set the code because the voltage or signal state did not match what it expected. Glow plug control module 2 is typically fitted to engines needing a second module, so layout and circuit details vary by model and engine.

Symptoms

Glow plug or engine management warning light on the dashboard
Hard starting or extended cranking on cold mornings
Rough running, white smoke or misfire after a cold start
Increased exhaust emissions or higher fuel consumption when cold
Engine running in a reduced-performance (limp) mode in some cases
No noticeable symptoms when the engine is warm

Possible causes

Damaged, chafed or shorted wiring on the control circuit between the ECU and glow plug control module 2, including a short to voltagelikely
Corroded, loose or damaged connector terminals at the control module or ECUlikely
Faulty glow plug control module 2 with an internal fault in its control input or driverlikely
Poor power or earth supply to the module causing an incorrect signal statepossible
Water ingress or heat damage affecting the module or its wiringpossible
Fault inside the engine ECU control outputrare
Outdated ECU software where the manufacturer has issued a known fix for the modelrare

How to diagnose

Read all stored and pending codes and note any other glow plug or module codes, then review freeze frame data for engine temperature and battery voltage
Check battery condition and charging voltage, as low or unstable voltage can upset module communication
Visually inspect the wiring, connectors and module location for chafing, heat damage, water ingress and corrosion
Check the relevant fuses and relays for the glow plug system using the model wiring diagram
Test the supply and earth at the glow plug control module 2 connector against the manufacturer data
Check the control circuit for short to voltage and for continuity and resistance between the ECU and module with the circuit isolated
Use a scan tool to run the glow plug system output test if supported and observe the module response
Check for applicable software updates or technical bulletins for the specific model and engine

How to fix

Repair or replace damaged wiring and fix any short to voltage on the control circuit
Clean, repair or replace corroded or damaged connectors and terminals
Replace glow plug control module 2 if tests show it is faulty, and code or adapt it if the model requires
Restore good power and earth connections to the module
Replace or repair the ECU only if the fault is confirmed within it
Update the ECU calibration only if an outdated version is a documented cause for that vehicle

Can I keep driving?

Medium severity

The car can usually be driven short term, but cold starting and emissions may suffer and it may enter reduced power. Have it checked soon, especially before cold weather.

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