Network, generic

U007C Control Module Communication Bus J Off

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

For U007C no manufacturer publishes a use; a Bus J only exists where the electrical architecture splits the vehicle into ten or more CAN segments. Bus off is self-healing by design: once the controller has seen 128 sequences of 11 recessive bits it may rejoin, as onsemi explains, and the error counters start again from zero. A short-lived short circuit, a loose pin or a voltage dip during cranking can therefore leave U007C as a history code while everything works again by the time the car reaches the workshop. Such intermittent cases need the fault reproduced, for instance by flexing harness sections and connectors of Bus J while watching the module's communication status. Replacing modules on a history code alone rarely helps.

Likely causes

Loose pin or connector on Bus J opening briefly
Voltage dip during engine cranking
Harness chafe causing brief shorts on Bus J

Symptoms

  • Stored history code without a current complaint
  • Brief, self-clearing dropouts of single functions

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–700
Time1–5 h

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

Parts involved

bus j wiringcan transceiver

Related codes

U007BU007DU009DU009E

References: onsemi.com, law.cornell.edu, en.wikipedia.org.