What Does P0AF2 Mean?
The motor controller has detected a general circuit malfunction in drive motor inverter temperature sensor B. This is a second temperature sensor on the inverter, typically monitoring a different IGBT module or phase leg than sensor A. Having multiple temperature sensors allows the controller to detect hot spots within the inverter. A circuit fault on sensor B reduces thermal monitoring coverage and may trigger power derating as a protective measure.
Safety Warning
Loss of inverter temperature sensor B means the controller has reduced thermal visibility on the inverter. Some systems will rely on sensor A alone with a reduced power limit, while others may disable the electric drive entirely. The vehicle should be serviced before sustained heavy-load driving to prevent potential inverter damage from unmonitored overheating.
Common Causes
30%
Failed inverter temperature sensor B (NTC thermistor open or shorted)
25%
Damaged wiring between the motor controller and sensor B
20%
Corroded or loose connector pins at the sensor B location
15%
Faulty motor controller temperature input channel for sensor B
10%
Sensor B displaced from heat sink mounting position
Diagnostic Steps
1
Read both inverter temperature sensors (A and B) with the scan tool. If sensor A reads normally and sensor B shows an extreme or impossible value, the fault is confirmed to sensor B's circuit.
2
Locate inverter temperature sensor B on the inverter assembly — it is typically on a different phase module or opposite side of the heat sink from sensor A. Inspect the connector for damage or disconnection.
3
Disconnect sensor B and measure its resistance — NTC thermistors typically read 5K-50K ohms at 25C. An open (OL) or shorted (near 0) reading confirms sensor failure.
4
Check wiring continuity and insulation resistance from the sensor B connector to the motor controller connector. Each wire should have less than 2 ohms and greater than 100K ohms to ground.
5
If the sensor and wiring test normal, substitute a known resistor at the motor controller's sensor B input to verify the input channel is functional.
Estimated Repair Cost
$200 - $1,800
Parts + labor, varies by vehicle and location
The motor controller has detected a general circuit malfunction in drive motor inverter temperature sensor B. This is a second temperature sensor on the inverter, typically monitoring a different IGBT module or phase leg than sensor A. Having multiple temperature sensors allows the controller to det...
The most common cause of P0AF2 (Drive Motor Inverter Temperature Sensor "B" Circuit) is: Failed inverter temperature sensor B (NTC thermistor open or shorted)
Typical repair costs for P0AF2 range from $200 to $1,800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of inverter temperature sensor B means the controller has reduced thermal visibility on the inverter. Some systems will rely on sensor A alone with a reduced power limit, while others may disable the electric drive entirely. The vehicle should be serviced before sustained heavy-load driving to prevent potential inverter damage from unmonitored overheating.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0AF2 to identify the root cause.
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Quick Info
Category
Powertrain
System
Hybrid/EV Drive Motor & Inverter
Difficulty
Type
Generic (SAE)
Recommended Tools
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