U0090Vehicle Communication Bus G (-) High
- Generic OBD-II code · Network
- Can trigger limp mode
- How the car detects it
- U0090 is logged when Bus G's (-) wire is pulled up, typically by a short to a supply feed; in CAN terms this is the CAN-Low line. U0090 is not described in any public manufacturer source. Unlike a grounded CAN-Low, this fault normally stops the bus: onsemi found transmission impossible with CAN-Low at 12 V, and NXP rates it as a short under which communication fails. The search is easier once you know which feed is involved. Nissan's CAN diagnostic chart measures each bus wire to ground both with the key off and with it on, and keeps separate entries for shorts to battery and to an ignition feed. A fault that is present only with the ignition on points to a switched circuit, one that persists with the key off to a permanent battery feed.
- What you may notice
- All modules on Bus G stop responding at once
- Warning lamps and lost-communication codes in several systems
- Fault may come and go with the ignition switch position
- Likely causes
- Likely(-) wire shorted to a permanent battery feed
- Possible(-) wire touching a switched ignition feed in the harness
- RareRetrofitted equipment spliced into the bus wires
- Repair
- Hard · Usually a job for a workshop.Typical cost: €60 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.