Powertrain, generic

P0E34 DC/DC Converter Voltage Sensor A High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

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.

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

Symptoms

  • MIL on after two trips (GM)
  • Engine auto-stop disabled

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

P0E31P0E32P0E33P0E35P0E39

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