Network, generic

U007F Control Module Communication Bus M Off

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U007F closes the range of bus-off codes that SAE runs from U0073 for Bus A to Bus M; the next code, U0080, already belongs to the general Bus F faults. No manufacturer publishes a use, and which physical network carries the letter M has to be read from the maker's service data. CARB only demands that missing digital communication be detected and stored separately, not how buses are named. One detail helps narrow the cause: according to Wikipedia, a sender whose frames simply go unacknowledged, for example because it is alone on the bus, keeps repeating them and reaches error passive, not bus off. U007F thus points to active disturbance, such as a shorted line or a node that cannot drive the bus. Begin at the storing module's supply, ground and connector.

Likely causes

Shorted line on Bus M
A node unable to drive the bus, e.g. defective transceiver
Poor supply, ground or connector contact at the storing module

Symptoms

  • Functions of the storing module unavailable
  • Several warning messages or none, depending on the module

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–800
Time0.5–5 h

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

Parts involved

bus m wiringcan transceiver

Related codes

U007EU0080U0073

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