P0E38DC/DC Converter Voltage Sensor B Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P0E38 is stored when the second voltage reading of the DC/DC converter, sensor B, sits at the bottom of its scale. GM uses it in the 2025 engine tables (25OBDG03A) with the same limits as on sensor A, only applied to raw voltage value 2: under 1 V, confirmed by 320 of 400 samples taken at 12.5 ms intervals and only checked at 6.6 V battery voltage or more. GM's description calls it a test for short to ground, and the result is Type B with the MIL on the second trip. Because GM uses two independent paths, a fault on just one of them points to that path's wiring or circuit rather than the converter output itself. Sensor A's low code is P0E33; P0E39 covers sensor B reading too high.
- What you may notice
- MIL on after two trips (GM)
- Auto stop/start inhibited
- Likely causes
- LikelySensor B signal wire shorted to ground
- PossibleFailed second measuring circuit in the converter
- RareBent or corroded pin in the converter connector
- 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.