What it means
The DC/DC converter temperature sensor A 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
DC/DC converter temperature sensor A monitors temperature at the converter, which helps supply the vehicle's lower-voltage electrical system from the high-voltage system. The control module monitors sensor A's electrical circuit for a valid signal. P0C38 sets when that circuit has a fault, though the code alone does not identify whether the signal is low or high.
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
- Review freeze-frame and live data for converter temperature sensor A, noting whether its reading is missing, fixed, or implausible.
- Inspect sensor A's connector and nearby wiring for looseness, corrosion, abrasion, or heat damage.
- Check the sensor A circuit for opens or shorts using the vehicle wiring diagram and manufacturer's procedures.
- Test sensor A and its wiring at the connector against the manufacturer's specifications.
- Repair the connection or wiring fault, or replace sensor A if it fails testing, then confirm converter temperature data is reliable.
Common fixes
- Secure or clean the converter temperature sensor A connector and repair damaged terminals.
- Repair open or shorted sensor A wiring.
- Replace sensor A if it fails the specified test.
Can I keep driving?
Keep trips short and avoid high electrical loads if the hybrid warning or limited operation is present, because the converter may restrict output to protect itself. Stop safely if the vehicle loses electrical functions or power drops substantially.
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.