P06FD code meaning
Glow Plug Control Module 2 to PCM Communication Circuit Range/Performance
Powertrain system Generic code P06xx codes Check engine light
What P06FD means
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.
P06FD at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P06FD
- 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
Common causes of P06FD
- Most likelyLoose contact or contact resistance in the feedback or bus line
- PossibleGround offset between module and engine module from glow currents
- Less likelySoftware mismatch between modules or module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Glow plug control module 2Glow plug feedback lineEngine control module
What each part of P06FD means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6 | Area: computer (engine control module) and output circuits. |
| FD | The exact fault in that area. |
What to do next
- Note P06FD and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P06FD
What does P06FD mean?
P06FD means "Glow Plug Control Module 2 to PCM Communication Circuit Range/Performance". 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 a generic code, so it means the same on every make.
Is it safe to drive with P06FD?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P06FD fail an emissions test?
Yes, it can. P06FD is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P06FD to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P06FD clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.