U008C code meaning
Vehicle Communication Bus G (+) Low
What U008C means
U008C indicates a (+) wire on Vehicle Communication Bus G pulled too low, usually grounded. No manufacturer documents U008C publicly. On a high-speed CAN the (+) wire is CAN-High, which Texas Instruments describes as rising from about 2.5 V to 3.5 V for every dominant bit while CAN-Low drops to 1.5 V, giving the 2 V difference receivers decode. A grounded CAN-High cannot rise, so no node can assert a dominant bit; onsemi saw transmission fail outright in this state. Each failed frame raises the sender's error counter, so the same module may also log U0079 once it goes bus off. The whole network falls silent and other networks log the missing modules. With the battery disconnected, CAN-High showing only a few ohms to chassis confirms the short.
U008C at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U008C
- All modules on Bus G drop out together
- Many warnings and lost-communication codes at once
Common causes of U008C
- Most likely(+) wire of Bus G chafed against body metal
- PossibleHarness pinched by a screw, panel or seat
- Less likelyDefective transceiver holding CAN-High to ground
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Bus g wiringCAN transceiver
What each part of U008C means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 8C | The exact fault in that area. |
What to do next
- Note U008C 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 U008C
What does U008C mean?
U008C means "Vehicle Communication Bus G (+) Low". U008C indicates a (+) wire on Vehicle Communication Bus G pulled too low, usually grounded. It is a generic code, so it means the same on every make.
Is it safe to drive with U008C?
Drive gently and only to a workshop. With U008C the car can go into limp mode (reduced power) to protect itself.
Will U008C fail an emissions test?
U008C 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 U008C to fix?
Difficulty: hard. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will U008C clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.