U301A code meaning
Control Module Wake-up Circuit A/Open
What U301A means
A wake-up circuit is a separate wire that rouses a sleeping module without bus traffic, for example when a charge cable is plugged in or another controller needs it. U301A reports that line A has lost continuity, so no valid signal reaches the input. Ford's 2019 hybrid OBD summary shows such a line in use: the battery energy control module relies on a hardwired charge wake-up signal before it runs its charging and contactor checks. No manufacturer documents U301A publicly. GM's PIT6198 for 2019–2022 Silverado and Sierra shows the consequence of a lost wake input at the ECM (circuit 5985, about 12 V with the BCM awake): other modules report U0100 and the service engine lamp comes on, with possible shift complaints. An open wake line usually means the module stays asleep or joins late.
U301A 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 U301A
- Module does not respond, other modules report lost communication
- Charging or a function that needs the wake-up does not start
Common causes of U301A
- Most likelyBroken wake-up wire or pushed-out connector pin
- PossibleCorroded or loose contact at the sending or receiving module
- PossibleSending module or charger not driving the wake-up output
- Less likelyBlown fuse in a supply-fed wake circuit
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Wakeup circuit aWakeup wiring
What each part of U301A means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 1A | The exact fault in that area. |
What to do next
- Note U301A 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 U301A
What does U301A mean?
U301A means "Control Module Wake-up Circuit A/Open". A wake-up circuit is a separate wire that rouses a sleeping module without bus traffic, for example when a charge cable is plugged in or another controller needs it. It is a generic code, so it means the same on every make.
Is it safe to drive with U301A?
U301A does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U301A fail an emissions test?
U301A 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 U301A to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U301A clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.