U3543High Voltage System Interlock Circuit O Low
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- With U3543, loop O has dropped under its minimum. Some plug designs let the fitter see the reason. An LG Electronics patent describes a high-voltage connector closed by turning a cover housing: the rotation moves an inner cap up or down so that the power terminals mate first and the shorter interlock tab last, while a scale on the plug housing shows how far the cover has turned. A cover left short of its end stop keeps the power pins engaged with the interlock still apart, exactly the picture of a low reading. No maker documents U3543. Turn each rotary plug on loop O fully home and check the scale.
- What you may notice
- High voltage stays off after work on HV plugs
- No ready mode
- Charging not possible
- Likely causes
- LikelyRotary HV plug on loop O not turned to its end position
- PossibleInterlock tab or socket in a loop O plug bent or pushed back
- PossibleLoop O wire shorted to ground
- Repair
- Hard · Usually a job for a workshop.Typical cost: €60 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.