P0E34: DC/DC Converter Voltage Sensor A High

With P0E34 the controller sees a voltage on sensor A of the DC/DC converter that is too high to be real, which points to the signal being shorted to a battery feed or another live wire. In GM's 2025 tables (25OBDG03A) the ECM flags it when raw voltage value 1 exceeds 28 V, far above anything a 12 V converter output should reach. Sampling and confirmation mirror the low case: 320 of 400 readings must fail, battery voltage must be 6.6 V or more, and as a Type B fault it needs two trips before the MIL lights. A real overvoltage of the converter would not normally reach that value, so the wiring and the sensing path come first. Low readings on the same sensor use P0E33; sensor B has P0E39 for the same fault.

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)
Engine auto-stop disabled

Most likely causes

Signal wire shorted to a battery feed or other live circuit
Lost reference ground of the measurement, signal floats high
Faulty measuring circuit in the converter

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 P0E34 means

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

Frequently asked questions

Can I keep driving with code P0E34?

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 P0E34?

The most common causes are: signal wire shorted to a battery feed or other live circuit; lost reference ground of the measurement, signal floats high; faulty measuring circuit in the converter.

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.