P0E39: DC/DC Converter Voltage Sensor B High

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.

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)
Start-stop switched off

Most likely causes

Sensor B signal shorted to a voltage-carrying wire
Open reference ground letting the signal float high
Failed measuring circuit for sensor B

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
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
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 P0E39 means

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

Frequently asked questions

Can I keep driving with code P0E39?

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 P0E39?

The most common causes are: sensor B signal shorted to a voltage-carrying wire; open reference ground letting the signal float high; failed measuring circuit for sensor B.

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.