What Does P0AF5 Mean?
The motor controller has detected that drive motor inverter temperature sensor B circuit voltage is above the maximum expected threshold. High voltage means high resistance in the NTC circuit, indicating an open sensor, broken wiring, or a disconnected connector. The controller cannot determine inverter temperature at the sensor B location and will apply protective power limits or disable the electric drive system.
Safety Warning
The electric drive may be disabled or severely power-limited. Without thermal monitoring at sensor B's location, the controller cannot detect overheating of that inverter section. Avoid heavy-load driving and have the sensor circuit repaired to restore full thermal protection and normal driving capability.
Common Causes
30%
Open NTC thermistor (internal failure)
30%
Broken wire or open connection in the sensor B circuit
25%
Disconnected or backed-out pin at sensor B connector or motor controller
15%
Motor controller input circuit failure (open pull-up resistor or ADC)
Diagnostic Steps
1
Read inverter temperature B — if it shows an extreme low value (e.g., -40C) or a fixed maximum count, this confirms an open circuit condition.
2
Inspect the sensor B connector for disconnection, backed-out pins, or broken locking tabs. Many inverter sensor connectors are subject to engine bay heat and vibration.
3
Disconnect sensor B and measure resistance — OL (open) confirms sensor failure. A normal reading (5K-50K ohms at 25C) means the fault is downstream in the wiring.
4
Check wiring continuity from sensor B to the motor controller, including any intermediate connectors or splices. Flex the harness while monitoring to catch intermittent opens.
5
If all external circuits test normal, substitute a known resistance at the motor controller input. If still reading high, the motor controller's input channel has an internal fault.
Estimated Repair Cost
$150 - $1,800
Parts + labor, varies by vehicle and location
The motor controller has detected that drive motor inverter temperature sensor B circuit voltage is above the maximum expected threshold. High voltage means high resistance in the NTC circuit, indicating an open sensor, broken wiring, or a disconnected connector. The controller cannot determine inve...
The most common cause of P0AF5 (Drive Motor Inverter Temperature Sensor "B" Circuit High) is: Open NTC thermistor (internal failure)
Typical repair costs for P0AF5 range from $150 to $1,800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The electric drive may be disabled or severely power-limited. Without thermal monitoring at sensor B's location, the controller cannot detect overheating of that inverter section. Avoid heavy-load driving and have the sensor circuit repaired to restore full thermal protection and normal driving capability.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0AF5 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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