P0E33: DC/DC Converter Voltage Sensor A Low

P0E33 means the controller reads an implausibly low value from voltage sensor A of a DC/DC converter, typically because the signal wire is shorted to ground. GM documents it in its 2025 engine control tables (25OBDG03A) for a converter that keeps the 12 V network stable while the engine restarts automatically: the raw voltage value 1 must drop below 1 V, and 320 failing samples out of 400 taken every 12.5 ms, about four seconds, are needed. The test runs with at least 6.6 V battery voltage in run/crank or accessory mode. GM rates it Type B, so the MIL comes on after two trips. P0E34 is the opposite case on the same sensor, P0E38 the matching fault on sensor B. Start-stop and the 12 V support can be limited.

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 no longer available
Possible 12 V voltage dips during engine restarts

Most likely causes

Sensor signal wire chafed through to ground
Voltage measurement inside the converter failed
Moisture in the converter connector bridging to ground

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 P0E33 means

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

Frequently asked questions

Can I keep driving with code P0E33?

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 P0E33?

The most common causes are: sensor signal wire chafed through to ground; voltage measurement inside the converter failed; moisture in the converter connector bridging to ground.

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.