P0E38 code meaning
DC/DC Converter Voltage Sensor B Low
Powertrain system Generic code P0Exx codes Check engine light
What P0E38 means
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.
P0E38 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0E38
- MIL on after two trips (GM)
- Auto stop/start inhibited
Common causes of P0E38
- Most likelySensor B signal wire shorted to ground
- PossibleFailed second measuring circuit in the converter
- Less likelyBent or corroded pin in the converter connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Dcdc voltage sensor bWiring harnessDcdc converter
What each part of P0E38 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 38 | The exact fault in that area. |
What to do next
- Note P0E38 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0E38
What does P0E38 mean?
P0E38 means "DC/DC Converter Voltage Sensor B Low". P0E38 is stored when the second voltage reading of the DC/DC converter, sensor B, sits at the bottom of its scale. It is a generic code, so it means the same on every make.
Is it safe to drive with P0E38?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0E38 fail an emissions test?
Yes, it can. P0E38 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0E38 to fix?
Difficulty: hard. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P0E38 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.