P0C3FDC/DC Converter Temperature Sensor B Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0C3F is stored when the voltage from the second temperature sensor of the DC/DC converter falls below the lowest plausible value. These sensors are normally NTC thermistors fed through a pull-up resistor, so a low voltage corresponds to an extremely hot reading; a short to ground or a shorted element produces exactly that. No manufacturer documents P0C3F publicly. GM uses the same logic for comparable hybrid thermistors, flagging a low circuit once the computed temperature reaches about 88 °C. Mercedes-Benz lists the opposite fault of the same sensor, P0C40, on the EQB and G-Class. CARB requires hybrid component inputs to be checked for out-of-range signals. The converter usually derates to protect itself, so 12 V charging suffers. Sensor A's low code is P0C3A.
- What you may notice
- Hybrid or EV system warning in the cluster
- 12 V battery warning or falling on-board voltage
- Reduced power or switched-off comfort consumers
- Likely causes
- LikelySensor B signal line shorted to ground in the converter or harness
- PossibleShorted thermistor B, usually only fixable by replacing the converter
- RareConverter actually overheating because its cooling fails
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.