B0129 code meaning
DC/AC Converter A High Voltage Power Outlet "C" Circuit/Open
What B0129 means
B0129 covers outlet C. Apart from wiring faults, the converter also cuts sockets on purpose when the load is too high. Ford's patent US11043801B2 gives limits of 20 A for the 120 V sockets and 30 A for the 240 V socket, and when total power exceeds the ceiling it de-energises sockets by priority, the lowest first. Ford's SSM 51498 for the 2023 Super Duty describes the resulting Pro Power Onboard Turned Off message after wattage thresholds were exceeded, which could only be cleared once the load was unplugged. A shutdown like that is not an open circuit: B0129 means the converter finds no intact path to socket C. Which socket that is, and any maker using B0129, is not public.
B0129 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of B0129
- Socket C stays dead even with no load connected
- Outlet message that cannot be cleared by unplugging and resetting
- Outlet circuits carry 120/240 V AC from a high-voltage source; work only with the system de-energised
Common causes of B0129
- Most likelyTerminal at outlet C overheated or burnt from heavy loads, contact lost
- PossibleHarness to outlet C open
- Less likelySwitching element for outlet C inside the converter defective
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Dc ac converter aHv outlet c
What each part of B0129 means
| B | Body system: airbags, seat belts, power seats, lights and climate control. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 29 | The exact fault in that area. |
What to do next
- Note B0129 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 B0129
What does B0129 mean?
B0129 means "DC/AC Converter A High Voltage Power Outlet "C" Circuit/Open". B0129 covers outlet C. It is a generic code, so it means the same on every make.
Is it safe to drive with B0129?
B0129 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will B0129 fail an emissions test?
B0129 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 B0129 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will B0129 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.