U007F code meaning
Control Module Communication Bus M Off
What U007F means
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.
U007F at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U007F
- Functions of the storing module unavailable
- Several warning messages or none, depending on the module
Common causes of U007F
- PossibleShorted line on Bus M
- PossibleA node unable to drive the bus, e.g. defective transceiver
- Less likelyPoor supply, ground or connector contact at the storing module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Bus m wiringCAN transceiver
What each part of U007F means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7F | The exact fault in that area. |
What to do next
- Note U007F 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 U007F
What does U007F mean?
U007F means "Control Module Communication Bus M Off". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with U007F?
U007F does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U007F fail an emissions test?
U007F 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 U007F to fix?
Difficulty: hard. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will U007F clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.