P0C39 code meaning
DC/DC Converter Temperature Sensor A Range/Performance
Powertrain system Generic code P0Cxx codes Check engine light
What P0C39 means
P0C39 is the plausibility check of DC/DC converter temperature sensor A: its reading lies within the electrical range but does not fit the converter's operating state or a second sensor. FCA uses it on the 2021 Ram 1500 with the 3.6 litre eTorque mild hybrid, where the code is called temperature sensor 1 performance. Bulletin 08-037-21 updates the HCP software and changes this code from a two-trip to a one-trip DTC, so the MIL can come on after a single fault. Sensor B, sensor 2 at Ram, has the matching code P0C3E. CARB requires rationality checks for such inputs. A drifting sensor or poor thermal contact is typical; outright circuit faults are reported as P0C38, P0C3A or P0C3B instead.
P0C39 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P0C39
- MIL, after one trip with updated Ram software
- Mild hybrid assist or 12 V supply reduced
Common causes of P0C39
- PossibleOutdated hybrid control software (Ram 1500 eTorque, bulletin 08-037-21)
- PossibleSensor A drifting or with poor thermal contact to the power stage
- Less likelyUneven cooling of the converter making the readings disagree
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Dcdc converter temp sensor aWiring harnessDcdc converter
What each part of P0C39 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| C | Area: hybrid propulsion. |
| 39 | The exact fault in that area. |
What to do next
- Note P0C39 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0C39
What does P0C39 mean?
P0C39 means "DC/DC Converter Temperature Sensor A Range/Performance". P0C39 is the plausibility check of DC/DC converter temperature sensor A: its reading lies within the electrical range but does not fit the converter's operating state or a second sensor. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C39?
Drive gently and only to a workshop. With P0C39 the car can go into limp mode (reduced power) to protect itself.
Will P0C39 fail an emissions test?
Yes, it can. P0C39 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0C39 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will P0C39 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.