P0AF1
Drive Motor Inverter Temperature Sensor A Circuit Intermittent/Erratic.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- A
- AreaHybrid propulsion
- F1
- FaultThe specific fault in that area
What it means
P0AF1 means the hybrid or electric vehicle control unit has seen an intermittent or erratic signal from drive motor inverter temperature sensor A. The reading may jump, drop out or change implausibly compared with the other inverter and coolant temperatures. Because the inverter temperature protects the power electronics, the system may reduce power or limit operation when it cannot trust the signal. Sensor location and the number of sensors depend on the model and drive system.
Symptoms
- Hybrid or EV system warning light on
- Reduced power or limp mode, especially under load
- Reduced or intermittent electric assist or regeneration
- Cooling fan or pump for the power electronics running harder than normal
- Fault coming and going, often with vibration or heat
- Possible failure to enter ready mode in some models
Possible causes
- Loose, corroded or damaged connector at the inverter temperature sensor or its harness pluglikely
- Chafed, stretched or intermittently open or shorted wiring between the sensor and the control unitlikely
- Faulty inverter temperature sensor, often integrated into the inverter assemblypossible
- Coolant moisture or contamination affecting the sensor circuit or connectorpossible
- Fault inside the inverter or motor control unit's sensor input circuitrare
- Low coolant level or poor circulation in the power electronics cooling circuit giving genuinely erratic temperaturespossible
How to diagnose
- Read all stored and pending codes plus freeze frame data, noting temperature, load, vehicle speed and whether other inverter or cooling codes are present.
- Check the power electronics coolant level, hoses and pump operation, and look for leaks, following the manufacturer's procedure.
- Using live data, compare inverter temperature sensor A with other inverter, motor and coolant temperatures on a cold car and watch for spikes or dropouts.
- Visually inspect the sensor harness and connectors for chafing, corrosion, moisture, bent pins and poor terminal tension, without touching any orange high-voltage cable.
- Wiggle-test the harness and connector gently with live data running to see if the reading jumps.
- Only a trained technician following the manufacturer's high-voltage isolation procedure should go further: then check sensor circuit resistance, continuity and short to earth or supply against specification.
- Check for relevant technical bulletins or software updates for the model, as the procedure depends on the vehicle.
- If wiring and cooling are sound, confirm whether the sensor is serviceable separately or part of the inverter assembly before condemning it.
How to fix
- Clean, repair or replace the damaged connector or terminals, and secure the harness.
- Repair or replace the faulty section of wiring and protect it from chafing.
- Replace the inverter temperature sensor or the inverter assembly if the sensor is not separately serviceable and is confirmed faulty.
- Top up and bleed the power electronics cooling circuit and repair any leak or pump fault found.
- Apply a manufacturer calibration update only if an outdated control unit software is a documented cause for the vehicle.
Can I keep driving?
The car can usually be driven cautiously a short way to a workshop, but expect reduced power or limp mode. Stop and seek help if there is a red warning, a temperature warning, a burning smell or loss of drive.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.