P2C46Battery Isolation/Voltage Stabilization Control Circuit High
- Generic OBD-II code · Powertrain
- Can trigger limp mode
- How the car detects it
- P2C46 is the opposite of P2C45: the control line of the battery isolation or voltage stabilization switch sits higher than expected, which points to a short to battery voltage, or, on a low-side driven relay, to an open circuit that leaves the sense input floating high. The consequence can be worse than with a low signal, because a switch that cannot be commanded may stay closed during restarts, so the supply dip the stage is meant to block reaches the electronics again; Ford's start-stop patent describes the main battery sagging to roughly 5–7 V while cranking. No manufacturer documents P2C46 openly, so the exact threshold is calibration-specific. Check for wires pinched against B+ cables, then for an open circuit, before replacing the isolator.
- What you may notice
- Fault indicator on
- Stop-start disabled
- Screens or radio may reset when the engine restarts
- Likely causes
- LikelyControl wire shorted to battery positive
- PossibleOpen circuit with low-side driver (input pulled high)
- PossibleIsolator internally defective
- RareControl module input or driver fault
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.