What it means
The DC/DC converter temperature sensor B circuit has a fault, so its reading may be unreliable.
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 steps high-voltage battery power down to supply the vehicle’s lower-voltage electrical system. The control module monitors temperature sensor B’s circuit and sets P0C3D when that circuit has a fault that makes its reading unreliable; the code does not by itself identify whether the fault is an open, short, or sensor failure. The converter may restrict output as a precaution.
Common causes
Most likely first.
- Faulty temperature sensor
- Open or shorted wiring
- Poor connector connection
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
- Save freeze-frame data and read live data for DC/DC converter temperature sensor B to note whether the value is missing, implausible, or fixed.
- With the vehicle powered down as specified by the manufacturer, inspect sensor B’s connector and terminals for looseness, corrosion, moisture, or damage.
- Follow sensor B’s wiring harness and check for chafing, pinching, heat damage, or a break that could open or short the circuit.
- Use the wiring diagram and manufacturer’s procedure to check sensor B circuit continuity and for shorts to ground or voltage.
- Test temperature sensor B’s response against the manufacturer’s specification and compare its reading with sensor A where applicable.
Common fixes
- Reconnect or clean sensor B’s connector and correct damaged terminals.
- Repair an open or short in sensor B’s wiring.
- Replace temperature sensor B if it fails the specified response test.
- Clear the code and verify sensor B reports a plausible temperature during operation.
Can I keep driving?
Drive only as needed if the vehicle remains controllable, and avoid long trips or demanding electrical loads because the converter may limit output. Stop safely if power drops sharply or the hybrid system issues a critical warning.
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.