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U030B Software Incompatibility With Glow Plug Control Module 2

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

U030B is the counterpart of U0307 for a second glow plug control module, used where an engine splits its glow plugs between two drivers, say one per bank. It is stored when the engine controller rejects the software or calibration identity of module 2, typically after only one of the two units was replaced or flashed. No manufacturer documents U030B publicly. A GM patent explains the dialogue behind it: glow plug faults are judged from several messages passed between engine and glow controller, with a strategy that changes with how long the plugs have been on in a drive cycle. GM also asks for the glow module software to be brought up to date after glow plug work (PIP5524). CARB requires glow plugs to be checked for proper response. U019C stands for lost contact, U049D for invalid data. Cold starts suffer; a MIL is likely.

Likely causes

Only glow module 2 (or only module 1) replaced, software levels now differ
Module of another part number or engine variant installed in position 2
Engine controller updated without the second glow module

Symptoms

  • Hard cold start, uneven running until warm
  • White smoke after starting in the cold
  • MIL and glow plug warning on

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–600
Time0.4–2 h

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

Parts involved

glow plug module 2ecmcontrol module software

Related codes

U019CU049DU0307P0380

References: law.cornell.edu, patents.google.com, static.nhtsa.gov, en.wikipedia.org.