P0AF4Drive Motor Inverter Temperature Sensor B Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0AF4 reports a signal of inverter temperature sensor B below the valid range. GM uses an NTC thermistor with a pull-up, so a low voltage reads as an inverter far hotter than possible, usually from a short to ground or an internal sensor fault in the motor B inverter. GM's thresholds: above 170 °C for 2.5 of 3.5 s, Type B, two trips, in the 2016 to 2019 hybrid tables; above 159 °C, Type A, one trip, in another 2019 table; above 130 °C, Type A, on the 2011 Volt; above 125 °C, Type B, on the 2011 and 2013 two-mode trucks. A genuine overheat is reported separately as an over-temperature code such as P0A3D or P0C14. Because the sensor sits inside the inverter, the fix is usually the inverter assembly.
- What you may notice
- Malfunction indicator lamp and hybrid warning
- Motor B power strongly limited
- Reduced hybrid assist and regeneration
- Likely causes
- LikelyShorted sensor or circuit inside the power inverter module
- PossibleSensor signal shorted to ground in external wiring, where present
- RareMoisture or coolant inside the inverter housing
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €300 – €5,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.