U301EControl Module Wake-up Circuit B/Open
- Generic OBD-II code · Network
- How the car detects it
- U301E is the open-circuit code for a second wake-up line, B, on modules that can be roused by more than one source, for example by a door or key event and separately by a charge or timer signal. Ford's patent US5945745A explains why such paths exist at all: a module may sit in a low-current state with the ignition off and still has to answer certain demands, such as panel lighting when the headlamps are switched on. No manufacturer documents U301E publicly; Ford's 2019 hybrid OBD summary shows only the A-side logic of a charge wake-up line. When only line B is open, the module still wakes through A and the bus but ignores the source wired to B, so the fault often shows as one specific function failing to start. If A and B are logged together, check the common sending module or a shared splice first.
- What you may notice
- One wake-dependent function, e.g. timed or remote action, does not start
- Module otherwise works normally once awake
- Likely causes
- LikelyBroken wake-up wire B or loose pin
- PossibleFault at a splice or sender shared with line A
- PossibleSource wired to line B not driving its output
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.