U301E code meaning
Control Module Wake-up Circuit B/Open
What U301E means
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.
U301E at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U301E
- One wake-dependent function, e.g. timed or remote action, does not start
- Module otherwise works normally once awake
Common causes of U301E
- Most 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
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Wakeup circuit bWakeup wiring
What each part of U301E means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 1E | The exact fault in that area. |
What to do next
- Note U301E and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U301E
What does U301E mean?
U301E means "Control Module Wake-up Circuit B/Open". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with U301E?
U301E does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U301E fail an emissions test?
U301E is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U301E to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U301E clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.