Powertrain, generic

P0E33 DC/DC Converter Voltage Sensor A Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

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

Symptoms

  • MIL on after two trips (GM)
  • Auto stop/start no longer available
  • Possible 12 V voltage dips during engine restarts

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–1,500
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

dcdc voltage sensor awiring harnessdcdc converter

Related codes

P0E31P0E32P0E34P0E35P0E38

References: gsi.ext.gm.com, law.cornell.edu.