P06FDGlow Plug Control Module 2 to PCM Communication Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P06FD means signals or messages from glow plug control module 2 arrive at the engine module but are implausible – wrong duty cycle or pattern, feedback not matching the command, or single messages timing out. It is the counterpart of P0684 for module 1; Saab's Bosch-based diesels, for example, expect the feedback signal to be inverse to the command line. No manufacturer document available to us uses a second glow module – Ford's and GM's V8 diesels drive all eight plugs from one; the code suits systems with one module per cylinder bank. The description follows module 1 (P0684). A missing signal or open line is P06FC, a lost bus link usually U0106. The plugs of module 2 then heat poorly or not at all, typically on one bank.
- What you may notice
- Check engine light, possibly glow plug/wait-to-start lamp
- Hard cold start, long cranking in frost
- Rough cold idle and white smoke, often one cylinder bank only
- Usually no symptoms when warm
- Likely causes
- LikelyLoose contact or contact resistance in the feedback or bus line
- PossibleGround offset between module and engine module from glow currents
- RareSoftware mismatch between modules or module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.