U0036 code meaning
Vehicle Communication Bus A (-) Shorted to Bus A (+)
What U0036 means
U0036 describes a short between the (+) and (-) wires of Vehicle Communication Bus A. On a CAN-type bus the differential voltage then stays at zero, receivers see only recessive bits and, as onsemi's measurements on high-speed CAN show, no frame can be sent any more; NXP adds that transceiver diagnosis cannot detect this short. Audi documents U003600 under exactly its J2012 name for the 2018-21 Q5 plug-in hybrid: together with U002800, U002900 and drive-motor and power-electronics codes it appears when the 12 V harness of the power electronics chafes against the underbody trim, with warning lamps and in some cases a car that cannot be driven. The fix is repairing the wires and rerouting the harness. With the battery off, near zero ohms between the bus wires confirms the short.
U0036 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0036
- Several warning lamps on at once
- Vehicle may refuse to drive (Audi Q5 PHEV)
- Drive-motor and power-electronics codes stored alongside
Common causes of U0036
- Most likelyHarness chafed so that both bus wires touch (Audi Q5 PHEV: underbody trim)
- PossibleWater in a splice or connector bridging the two wires
- Less likelyDamaged transceiver shorting its bus pins
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Bus a wiring
What each part of U0036 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 36 | The exact fault in that area. |
What to do next
- Note U0036 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 U0036
What does U0036 mean?
U0036 means "Vehicle Communication Bus A (-) Shorted to Bus A (+)". U0036 describes a short between the (+) and (-) wires of Vehicle Communication Bus A. It is a generic code, so it means the same on every make.
Is it safe to drive with U0036?
Drive gently and only to a workshop. With U0036 the car can go into limp mode (reduced power) to protect itself.
Will U0036 fail an emissions test?
U0036 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 U0036 to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will U0036 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.