U01B8Lost Communication With Switch Input Module B
- Generic OBD-II code · Network
- How the car detects it
- Carmakers that fit more than one switch input module count them A, B, C. A modular layout patented by BCS Automotive Interface Solutions shows why there can be several: a main switch module, for example for the lighting, is extended by satellite modules of different kinds, and coding contacts in the connectors tell the main unit which type is plugged in. U01B8 means the second module, B, has gone silent while the others may still work normally. The allocation is specific to each vehicle, and no maker documents U01B8 publicly, so the wiring diagram decides which buttons are affected. Check supply, ground, bus wires and connector of module B before replacing it. The driver sees only the buttons of module B fail. U04BB covers implausible data, U01B7 and U01B9 the siblings.
- What you may notice
- Buttons served by module B without function
- Other switch groups still working
- Likely causes
- LikelyConnector of module B unplugged, loose or corroded
- PossibleMissing supply voltage or ground at module B
- RareSwitch input module B faulty
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.