Open circuit, damaged wiring or poor connection between the converter and outlet 'C'; Faulty or damaged outlet socket, or an internal fault in its sensing or interlock circuit; Corrosion or water ingress in the outlet or its connector; Blown protection device or tripped circuit protection in the outlet feed; Fault inside DC/AC converter A; Control module fault or software issue affecting outlet monitoring, only if a manufacturer update is known for this fault.

B0129

DC/AC Converter A High Voltage Power Outlet “C” Circuit/Open.

Generic
Body
Generic code
Low severity

How this code is built

B: SystemBody
0: Defined bySAE, the same on every car
1: AreaBody area 1
29: FaultThe specific fault in that area

What it means

B0129 is a body-system code meaning the control unit has found a circuit fault or open circuit in the high voltage power outlet 'C' supplied by DC/AC converter A. This is the feature that provides a household-style mains socket on some hybrid and electric vehicles. The module monitoring the converter output saw no expected current path, voltage or feedback signal on that outlet circuit. The exact layout, and which outlet is 'C', depends on the model.

Symptoms

Vehicle power outlet 'C' gives no power
Warning light or message about the power outlet or external power supply
Outlet works intermittently or cuts out when a load is plugged in
Other outlet or converter fault codes stored alongside
Normal driving is usually unaffected

Possible causes

Open circuit, damaged wiring or poor connection between the converter and outlet 'C'likely
Faulty or damaged outlet socket, or an internal fault in its sensing or interlock circuitlikely
Corrosion or water ingress in the outlet or its connectorpossible
Blown protection device or tripped circuit protection in the outlet feedpossible
Fault inside DC/AC converter Apossible
Control module fault or software issue affecting outlet monitoring, only if a manufacturer update is known for this faultrare

How to diagnose

Record the freeze frame data and check for other stored codes, especially high voltage system, converter or battery codes, before clearing anything.
Check the manufacturer's service information for this model: how outlet 'C' is fitted, how it is enabled, and the high voltage safety procedure.
Visually inspect outlet 'C', its cover and connector for water, corrosion, heat marks, bent pins or physical damage.
Confirm the outlet feature is switched on and the vehicle is in the right state to supply power, as the settings or conditions vary by model.
Test with a known-good, low-power load to see whether the fault is load-related or constant.
Check the relevant fuses or protection devices and inspect the accessible low voltage wiring and connectors for chafing or loose pins.
Only a suitably trained technician with the correct high voltage isolation procedure should test or disconnect high voltage wiring and check for continuity or insulation faults.
After repair, clear the code and retest the outlet under load to confirm the code does not return.

How to fix

Repair or replace damaged wiring or connectors in the outlet circuit, following the manufacturer's procedure.
Replace the faulty outlet socket or its sensing components.
Dry, clean and properly seal a corroded or water-affected connector, and replace it if the terminals are damaged.
Replace a blown fuse or protection device only after finding and fixing the cause.
Repair or replace DC/AC converter A if testing confirms an internal fault.
Update the module software only if the manufacturer lists it as a fix for this fault.

Can I keep driving?

Low severity

The car can normally be driven as the fault only affects the power outlet, but do not use that outlet. If any hybrid or electric drive system warning is also showing, or you see signs of heat, burning smell or water damage near the outlet, stop and get it checked by a qualified technician.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.