P0AF3: Drive Motor Inverter Temperature Sensor B Circuit Range/Performance

What it means

The control module detects a signal from the drive motor inverter temperature sensor B that is outside the expected range or does not match expected performance.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

Inverter temperature sensor B measures the drive motor inverter’s temperature for the control module. P0AF3 sets when the signal is electrically plausible but its value or response falls outside the expected range or performance pattern, which can happen if the sensor has drifted or is not mounted correctly.

Common causes

Most likely first.

1. Sensor characteristic drifted
2. Sensor mounting displaced
3. Sensor element aged beyond calibration window

Symptoms

• EV/hybrid system warning light on
• Reduced motor power or torque
• Possible limp mode or vehicle shutdown

How to diagnose it

1. Review freeze-frame and live data for sensor B alongside other inverter temperature readings to identify when and how its value diverges.
2. Inspect sensor B’s mounting and contact with the inverter, checking for displacement, looseness, or anything that could interfere with temperature sensing.
3. Check the sensor B connector and wiring for damage, corrosion, or poor contact that could distort the reading.
4. Compare sensor B’s response with the manufacturer’s specified temperature and operating conditions to assess whether it tracks temperature correctly.
5. If mounting and wiring are sound, test sensor B against the manufacturer’s specification and replace it if its characteristics are outside the permitted range.

Common fixes

• Secure sensor B in its specified mounting position.
• Repair a damaged or poorly connected sensor B connector or wire.
• Correct poor sensor contact with the inverter where the manufacturer’s procedure allows.
• Replace sensor B if it has drifted outside the manufacturer’s specified response range.

Can I keep driving?

Limit driving until the reading is checked, since the hybrid system may reduce torque or enter limp mode. Avoid hard acceleration and long trips; a shutdown or loss of drive power is possible.