U0068 code meaning
Vehicle Communication Bus E (+) High
What U0068 means
U0068 flags the (+) wire of Vehicle Communication Bus E at an excessive voltage, from battery or a 5 V rail. If Bus E is a high-speed CAN, the line in question is CAN-High, and traffic continues: onsemi saw frames pass with altered dominant levels, NXP files the case under hidden failures. Detecting it therefore depends on the module. NXP's TJA1041 note explains that a diagnosing transceiver must itself send at least four sufficiently long dominant phases before its failure flag is valid, and recommends reading the flag once a frame has finished, because arbitration with other senders can distort the measurement. That is why only some modules on Bus E, or none, may store the code. No manufacturer documents U0068 publicly. A meter on CAN-High showing roughly supply voltage to ground proves it.
U0068 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 U0068
- Usually no symptom, code found by chance
- Code stored in only one module on Bus E
Common causes of U0068
- Most likely(+) wire of Bus E chafed against a battery or 5 V feed
- PossibleMoisture in a connector bridging the bus wire to supply
- Less likelyAftermarket device connected to the bus wire
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Bus e wiringCAN transceiver
What each part of U0068 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 68 | The exact fault in that area. |
What to do next
- Note U0068 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 U0068
What does U0068 mean?
U0068 means "Vehicle Communication Bus E (+) High". U0068 flags the (+) wire of Vehicle Communication Bus E at an excessive voltage, from battery or a 5 V rail. It is a generic code, so it means the same on every make.
Is it safe to drive with U0068?
U0068 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0068 fail an emissions test?
U0068 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 U0068 to fix?
Difficulty: hard. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will U0068 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.