OBD-II code B0127 indicates an open-circuit fault detected in the DC-to-AC converter (inverter) that supplies the vehicle's high-voltage AC power outlet. The body control module monitors the inverter output circuit and sets this code when continuity is lost or voltage is absent where expected. This code is specific to vehicles equipped with an onboard 120V AC household-style outlet powered from the high-voltage battery pack.
The inverter itself is the most common failure point. Internal circuitry degrades and can no longer produce 120V AC output, triggering the open-circuit detection in the body control module.
Broken, chafed, or corroded conductors in the high-voltage AC harness, or a loose/corroded connector at the inverter or outlet, frequently produces an open-circuit reading even when the inverter is good.
The interior outlet itself can fail internally (open contacts, broken thermal fuse inside the receptacle assembly), which the module sees as an open circuit on its output side.
A protective fuse or fusible link on the AC output side of the inverter can blow, opening the circuit and setting the code without any component failure.
If the inverter is not being commanded on, or the high-voltage DC supply is outside spec, the output will read as open to the body control module.
An internal fault in the BCM or its power outlet monitoring logic can falsely flag an open circuit. This is uncommon and should only be considered after the inverter, wiring, outlet, and fuses have been verified.
In most cases the vehicle will continue to drive normally because the inverter only powers the accessory outlet, not the traction system. The outlet should not be used until the fault is repaired, and the underlying cause should be diagnosed promptly.
A blown fuse or a damaged wire is a common and inexpensive cause. The inverter is the most frequent single component to fail, but it is not the only possibility, which is why wiring, fuses, and the outlet should all be checked first.
No. B0127 is a body-system code generated by the body control module monitoring the inverter output, and the engine computer (PCM/ECM) is not involved. Replacing the PCM will not fix this code. The BCM itself is also a rare cause; the inverter, wiring, outlet, and fuses should be verified first.
Some outlets have a manual reset button (similar to a household GFCI) that can restore operation if it has tripped. The diagnostic trouble code generally does not clear on its own and will require a scan tool to clear after the underlying fault is repaired.