Powertrain, generic · Hybrid propulsion

P0C3A DC/DC Converter Temperature Sensor A Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0C3A means the signal of DC/DC converter temperature sensor A is below its valid range. Low refers to the signal voltage: with an NTC thermistor and pull-up, as GM uses for its hybrid temperature sensors, a short to ground or a failed element reads as extreme heat. No manufacturer documents P0C3A publicly. Mercedes-Benz shows the opposite case for the same sensor, P0C3B as a short to positive, on the EQB and the G-Class, and Ram the plausibility code P0C39. CARB requires the converter's inputs to be checked for out-of-range values. Because the controller must assume an overheated power stage, it limits or stops the converter output; the 12 V battery then supplies the car alone and a low-voltage warning may follow. The sensor is usually built into the converter.

Likely causes

Sensor A signal shorted to ground inside the converter or its harness
Shorted temperature element A, usually requiring converter replacement
Converter really overheated due to a cooling fault

Symptoms

  • Hybrid or EV system warning
  • 12 V battery warning, system voltage dropping
  • Reduced power or restricted functions

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–2,500
Time1–4 h

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

Parts involved

dcdc converter temp sensor awiring harnessdcdc converter

Related codes

P0C3BP0C38P0C39P0C3CP0C3FP0D32

References: law.cornell.edu, static.nhtsa.gov, gsi.ext.gm.com.