What it means
The DC/DC converter temperature sensor A circuit signal is intermittent or erratic.
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 changes high-voltage battery power into lower-voltage power for the vehicle’s electrical system. The control module watches temperature sensor A’s signal for sudden or unstable changes and sets P0C3C when that signal becomes intermittent or erratic. The converter may limit output if it cannot rely on the temperature reading.
Common causes
Most likely first.
- Loose or poor sensor connector
- Intermittent wiring fault
- Faulty temperature sensor
Symptoms
- Hybrid-system warning light may illuminate
- Intermittent reduction in power or hybrid operation
- DC/DC converter may limit output to protect itself
How to diagnose it
- Record freeze-frame data and check live data for DC/DC converter temperature sensor A to see when its reading jumps or drops out.
- With the vehicle powered down according to the manufacturer’s procedure, inspect sensor A’s connector for looseness, corrosion, moisture, or damaged terminals.
- Trace sensor A’s wiring for chafing, pinching, heat damage, or a loose harness connection, especially where movement could interrupt the signal.
- Monitor sensor A’s live reading while gently moving accessible wiring and the connector to see whether the signal becomes unstable.
- Test sensor A’s circuit and sensor response for continuity or dropouts using the manufacturer’s procedure, then compare readings with sensor B if the service information supports it.
Common fixes
- Secure or clean sensor A’s connector and repair damaged terminals.
- Repair an intermittent open or short in sensor A’s wiring.
- Replace DC/DC converter temperature sensor A if its signal drops out during testing.
- Clear the code and confirm sensor A’s reading stays stable through a repeat operating cycle.
Can I keep driving?
Avoid relying on the vehicle for long trips or heavy electrical loads while hybrid operation or power is reduced. If the hybrid warning appears with a major loss of power, stop somewhere safe; continued operation may cause the converter to limit output further.
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.