U0036Vehicle Communication Bus A (-) Shorted to Bus A (+)
- Generic OBD-II code · Network
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- Several warning lamps on at once
- Vehicle may refuse to drive (Audi Q5 PHEV)
- Drive-motor and power-electronics codes stored alongside
- Likely causes
- LikelyHarness chafed so that both bus wires touch (Audi Q5 PHEV: underbody trim)
- PossibleWater in a splice or connector bridging the two wires
- RareDamaged transceiver shorting its bus pins
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.