Powertrain, generic · Hybrid propulsion

P0C3D DC/DC Converter Temperature Sensor B Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0C3D is the general circuit code for the second temperature sensor of the DC/DC converter, which turns high-voltage battery power into 12 V supply. Converters with two sensors watch separate parts of the power stage or cross-check one sensor against the other. No manufacturer documents P0C3D publicly. Sensor B itself appears in bulletins: Mercedes-Benz lists P0C4000, a short to positive of sensor B, on the EQB and the G-Class, and Ram the plausibility code P0C3E as temperature sensor 2 on the 2021 1500 eTorque. Sensor A uses P0C38 for the same fault class. CARB requires such converter inputs to be monitored. A circuit fault makes the controller limit or stop the converter, so the 12 V battery may run down and warnings follow.

Likely causes

Connector or wiring fault in the sensor B circuit
Failed temperature element B inside the converter
Converter or hybrid control software misjudging the sensor

Symptoms

  • Hybrid or EV system warning
  • 12 V battery warning

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time0.5–4 h

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

Parts involved

dcdc converter temp sensor bwiring harnessdcdc converter

Related codes

P0C3EP0C3FP0C40P0C41P0C38

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.