P0E38: 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. 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.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

MIL on after two trips (GM)
Auto stop/start inhibited

Most likely causes

Sensor B signal wire shorted to ground
Failed second measuring circuit in the converter
Bent or corroded pin in the converter connector

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
With the connector unplugged, check whether the signal wire is making contact with ground.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

Repair difficulty: hard
It affects emissions.

What each character of P0E38 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
E: Subsystem depends on the code range
38: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0E38?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0E38?

The most common causes are: sensor B signal wire shorted to ground; failed second measuring circuit in the converter; bent or corroded pin in the converter connector.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.