What it means
The ECM detects a circuit high 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 measures heat at its DC/DC converter location and sends a signal to the ECM for thermal control. This circuit-high code sets when the signal is above the expected electrical range, which can occur with a signal short to battery voltage, an open sensor, or poor connector contact.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- 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
- Save freeze-frame data and compare sensor F live data with other converter temperatures to see whether it is implausibly high, fixed, or unavailable.
- With the hybrid system powered down according to service information, inspect sensor F's connector for corrosion, backed-out pins, looseness, or moisture.
- Inspect the sensor F harness for damage and check whether its signal wire has contacted a power feed.
- Test the signal circuit for an open and for an unintended connection to battery voltage using the vehicle wiring information.
- Check sensor F's resistance or output against the manufacturer's specification to confirm whether the sensor itself is open.
Common fixes
- Restore proper terminal contact at sensor F's connector.
- Repair an open signal wire or a short to battery voltage.
- Replace sensor F if it is open or fails the manufacturer's specification.
- Repair a confirmed fault at the ECM connector or circuit.
Can I keep driving?
Limit driving and avoid heavy loads because the hybrid system may reduce power when converter temperature feedback is unreliable. Stop if a hybrid temperature warning appears or the vehicle's power drops sharply.
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.