U007C code meaning
Control Module Communication Bus J Off
What U007C means
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.
U007C at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U007C
- Stored history code without a current complaint
- Brief, self-clearing dropouts of single functions
Common causes of U007C
- PossibleLoose pin or connector on Bus J opening briefly
- PossibleVoltage dip during engine cranking
- Less likelyHarness chafe causing brief shorts on Bus J
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Bus j wiringCAN transceiver
What each part of U007C means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7C | The exact fault in that area. |
What to do next
- Note U007C 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 U007C
What does U007C mean?
U007C means "Control Module Communication Bus J Off". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with U007C?
U007C does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U007C fail an emissions test?
U007C is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U007C to fix?
Difficulty: hard. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will U007C clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.