What it means
The control module detects a high electrical signal in the drive motor inverter temperature sensor B circuit. This indicates a circuit or sensor signal fault, not necessarily that the inverter itself is overheating.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Temperature sensor B reports drive motor inverter temperature through an electrical signal monitored by the control module. P0AF5 sets when the signal is higher than the circuit’s expected electrical range, which can result from a short to voltage or an open circuit; it does not confirm that the inverter is overheating.
Common causes
Most likely first.
- Signal wire shorted to voltage
- Open sensor or circuit
- Poor connector contact
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Review freeze-frame and live data for sensor B to see whether its signal is stuck high, and check for related hybrid-system codes.
- With the vehicle powered down under the manufacturer’s high-voltage safety procedure, inspect sensor B’s connector and wiring for an open, loose terminal, or contact with a voltage source.
- Check the sensor B signal wire for an open circuit or short to voltage using the manufacturer’s diagnostic procedure.
- Test sensor B and its circuit against the manufacturer’s specification to tell a sensor fault from a wiring or connector fault.
- After repairs, verify that sensor B data changes plausibly and the high-signal fault does not recur.
Common fixes
- Reconnect and secure a loose sensor B connector.
- Repair an open or damaged wire in the sensor B circuit.
- Correct a sensor B signal wire shorted to voltage.
- Replace sensor B if it fails the manufacturer’s specified test.
Can I keep driving?
Limit driving because the hybrid system may reduce power or shut down if it cannot trust the inverter temperature reading. Avoid hard acceleration and stop safely if power is reduced or a warning escalates.
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.