P0E39DC/DC Converter Voltage Sensor B High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P0E39 reports that sensor B of the DC/DC converter reads far too high, a pattern GM attributes to a short to battery. The 2025 engine tables (25OBDG03A) set the bar at more than 28 V for raw voltage value 2, again needing 320 failing samples within 400 at 12.5 ms and a battery voltage of at least 6.6 V, with Type B confirmation over two trips. If only sensor B shows the excess while sensor A and the ECM's own run/crank reading stay normal, a wiring fault on the B path is far more likely than a converter that really puts out such a voltage. A lost reference ground can also let the signal float upward. Sensor A's high code is P0E34; a low reading on sensor B is P0E38, an implausible but valid one P0E37.
- What you may notice
- MIL on after two trips (GM)
- Start-stop switched off
- Likely causes
- LikelySensor B signal shorted to a voltage-carrying wire
- PossibleOpen reference ground letting the signal float high
- RareFailed measuring circuit for sensor B
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.