What Does P0AF0 Mean?
The motor controller has detected that the drive motor inverter temperature sensor A circuit voltage is above the maximum expected threshold. High voltage on an NTC circuit means high resistance, indicating either an open sensor, an open circuit in the wiring, or an extremely cold reading that is not physically plausible. The motor controller loses its ability to monitor inverter temperature and will typically derate the system or set a protective power limit.
Safety Warning
Without temperature monitoring, the motor controller cannot protect the inverter from overheating and will typically apply a conservative power limit. The vehicle may have significantly reduced acceleration and may not be able to maintain highway speeds under load. Do not push the vehicle hard until the sensor is repaired, as the lack of thermal protection could lead to inverter damage.
Common Causes
30%
Open NTC thermistor (internal failure causing infinite resistance)
30%
Broken wire or open circuit in the sensor harness
25%
Disconnected or backed-out connector pin at the sensor or motor controller
15%
Faulty motor controller input circuit (open pull-up resistor or ADC failure)
Diagnostic Steps
1
Read inverter temperature A — if it reports an implausibly low value (e.g., -40C or below) or shows a fixed maximum reading, this confirms an open circuit condition.
2
Inspect the sensor connector at the inverter for a disconnected plug, backed-out pin, or corrosion that prevents electrical contact. Verify the locking mechanism is engaged.
3
Disconnect the sensor and measure resistance — an open reading (OL) confirms sensor failure. If normal (5K-50K ohms at 25C), the problem is in the wiring or motor controller.
4
Check wiring continuity from the sensor connector to the motor controller connector pin-for-pin. Flex the harness while monitoring to detect intermittent breaks.
5
If the sensor and wiring are intact, substitute a known resistor value at the motor controller input. If the reading is still incorrect, the motor controller's input circuit has failed.
Estimated Repair Cost
$150 - $1,800
Parts + labor, varies by vehicle and location
The motor controller has detected that the drive motor inverter temperature sensor A circuit voltage is above the maximum expected threshold. High voltage on an NTC circuit means high resistance, indicating either an open sensor, an open circuit in the wiring, or an extremely cold reading that is no...
The most common cause of P0AF0 (Drive Motor Inverter Temperature Sensor "A" Circuit High) is: Open NTC thermistor (internal failure causing infinite resistance)
Typical repair costs for P0AF0 range from $150 to $1,800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Without temperature monitoring, the motor controller cannot protect the inverter from overheating and will typically apply a conservative power limit. The vehicle may have significantly reduced acceleration and may not be able to maintain highway speeds under load. Do not push the vehicle hard until the sensor is repaired, as the lack of thermal protection could lead to inverter damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0AF0 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
OBD2 Scanner
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