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DTC codes / P06xx · Computer and output circuits / P06F5

P06F5Glow Plug Control Module 2

P06F5 indicates that the powertrain control module has detected a fault within the glow plug control module 2 circuit, which is responsible for energizing the glow plugs on engines that use a second module for additional cylinders. The code is stored when the module's feedback signal does not match the commanded state, indicating an open, short, or internal module failure.

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 extended cranking when the engine is cold
  • Rough idle or misfire immediately after a cold start
  • White smoke from the exhaust during cold running
  • Reduced engine performance or power under load while the engine is warming up

Common causes, most likely first

  1. Faulty glow plug control module 2
  2. Damaged or corroded wiring harness or connector at the module
  3. Open or shorted glow plug circuit on one or more cylinders controlled by module 2
  4. Blown fuse or poor ground connection for the module
  5. Corrosion or water intrusion into the module connector
  6. Failed glow plug causing excessive current draw that damages the module

How to diagnose and fix it

  1. Inspect the glow plug control module 2 connector and wiring for corrosion, chafing, or loose pins
  2. Check the fuse and ground connections for the module using a digital multimeter
  3. Measure resistance of each glow plug controlled by module 2 and compare to specifications
  4. Test the control signal and feedback signal at the module connector with a multimeter or oscilloscope
  5. If wiring and glow plugs are good, replace glow plug control module 2
  6. Clear the diagnostic trouble codes and verify the repair with a cold-start test

What a P06F5 code really tells you

  • A failed glow plug can take out the control module, so always test the plugs before replacing the module to avoid repeat failure.
  • The code can set intermittently due to a poor ground connection that only acts up in cold or damp weather.
  • Some vehicles use a single module for all glow plugs, so P06F5 may not appear; this code is specific to systems with two modules.
  • A weak battery or charging system fault can cause the module to log this code without any actual module failure.
  • The glow plug control module 2 often shares a power feed with other circuits, so a blown fuse may affect more than just the glow plugs.

Can I keep driving with P06F5?

You can usually drive the vehicle, but cold starting may be difficult and prolonged driving with a faulty glow plug system can lead to excessive exhaust smoke and engine wear. Avoid heavy acceleration until the engine is fully warmed up, and repair the fault promptly to prevent further damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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