U0038Vehicle Communication Bus B Performance
- Generic OBD-II code · Network
- Can trigger limp mode
- How the car detects it
- U0038 flags Vehicle Communication Bus B as present but unreliable: frames arrive late, incompletely or for a while not at all, rather than the bus being dead outright. Volkswagen's 2014 Touareg data book describes the trigger as a global time-out in which no messages come in any longer. Honda uses U0038 for the TM-CAN link between transmission and engine control: on 2016-17 Civic CVT models it appeared together with U0101 when an internal TCM fault cut the link, leaving the car stuck in Park without cranking and with several warning lamps lit. Honda replaces the TCM and on 2016 cars also updates the PCM software. Compared with U0037 the code describes a bus that still exists but whose traffic breaks off, so intermittent contacts, a failing node or software are the usual suspects.
- What you may notice
- Selector stuck in Park, engine does not crank (Honda Civic CVT)
- Several warning lamps on at once
- Functions drop out intermittently
- Likely causes
- LikelyInternal fault in a module on Bus B (Honda Civic: transmission control module)
- PossibleLoose or corroded terminals interrupting traffic now and then
- PossibleSoftware mismatch between modules on the bus
- Repair
- Hard · Usually a job for a workshop.Typical cost: €60 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.