What it means
The DC/DC converter temperature sensor B signal is outside the expected range or does not behave as expected.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The DC/DC converter converts high-voltage battery energy to lower-voltage power for vehicle systems. The control module checks whether temperature sensor B’s reading stays within its expected range and changes plausibly; P0C3E is set when the value is out of range or its behavior does not match expectations. A misplaced sensor or a circuit fault can make the reported temperature differ from the converter’s actual temperature.
Common causes
Most likely first.
- Faulty temperature sensor
- Sensor wiring or connector fault
- Sensor incorrectly positioned
Symptoms
- Hybrid-system warning light may illuminate
- Reduced power or limited hybrid operation
- DC/DC converter may limit output to protect itself
How to diagnose it
- Check freeze-frame data and live data for sensor B to see whether the reading is implausible, stuck, or inconsistent with operating conditions.
- With the vehicle powered down according to the manufacturer’s procedure, inspect temperature sensor B and verify it is seated and positioned as specified.
- Inspect sensor B’s connector and nearby wiring for corrosion, loose terminals, abrasion, pinching, or heat damage.
- Compare sensor B’s live reading with sensor A and other available temperature data under similar conditions to identify an outlier.
- Test sensor B and its circuit against the manufacturer’s specifications, including signal continuity and sensor response as temperature changes.
Common fixes
- Reposition and secure sensor B if it is not installed as specified.
- Clean or repair sensor B’s connector and damaged wiring.
- Replace sensor B if its reading remains out of range despite a sound circuit and correct installation.
- Clear the code and confirm sensor B tracks temperature plausibly during operation.
Can I keep driving?
Limit driving to what is necessary if hybrid operation or power is reduced, and avoid heavy electrical demand. Stop safely if the vehicle loses substantial power, since the converter may further restrict output to protect itself.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.