Powertrain, generic · Computer and auxiliary outputs

P06FC Glow Plug Control Module 2 to PCM Communication Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P06FC means the feedback or communication from glow plug control module 2 to the engine module is missing, or the line is open or shorted – the counterpart of P0683 for module 1. Depending on design the module reports over a single feedback wire (Bosch-type systems expect it inverse to the command line) or over the bus; GM and Ford report a lost bus link as U0106 rather than P0683. 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 (P0683). The engine module then loses the plug status reports; implausible messages are P06FD. The plugs of module 2 then heat poorly or not at all, typically on one bank.

Likely causes

Feedback or bus line open or shorted, connector corroded
Glow module 2 without supply (does not transmit)
Glow module 2 or engine module interface faulty

Symptoms

  • 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

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–600
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

glow plug control module 2glow plug feedback lineengine control module

Related codes

P0683P06FDP06F6P06F9U0106

References: law.cornell.edu, fordservicecontent.com, gsi.ext.gm.com, patents.google.com.