What it means
The ECM detects a circuit low fault on the dc/dc converter temperature sensor f circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Temperature sensor F reports DC/DC converter heat to the ECM so it can manage the converter's thermal operation. This circuit-low code sets when the sensor F signal is below the expected electrical range, which can result from a signal short to ground, an internally shorted sensor, or poor connector contact.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light or hybrid-system warning
- Reduced hybrid power or performance
- Hybrid-system temperature warning
How to diagnose it
- Record freeze-frame data and inspect sensor F live data for an abnormally low or fixed reading compared with other converter temperatures.
- With the hybrid system safely powered down per service information, inspect sensor F's connector for corrosion, pushed-back pins, moisture, or weak contact.
- Trace the sensor F signal wire for damage or contact with ground, paying particular attention to rubbed or pinched sections.
- Check the sensor F signal and ground circuits for an unintended short to ground, following the vehicle wiring information.
- Test sensor F and its circuit response against the manufacturer's specification to determine whether the sensor is shorted internally or the wiring is at fault.
Common fixes
- Clean or repair corroded sensor F connector terminals and restore proper contact.
- Repair a signal wire shorted to ground or damaged harness section.
- Replace sensor F if it is internally shorted or outside the manufacturer's specification.
- Repair a confirmed fault in the ECM-side circuit.
Can I keep driving?
Avoid demanding acceleration and long trips because the ECM may limit hybrid output when it cannot trust sensor F's temperature signal. Stop safely if a hybrid-system temperature warning appears or power falls 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.