P0A31: Drive Motor B Temperature Sensor Circuit Range/Performance

P0A31 checks whether the motor B temperature reading makes sense, typically after a long rest when all parts should be close to the same temperature. GM compares it with other temperatures: the 2011 tables flag a gap above 20 °C to the average of power-electronics coolant and transmission fluid after 6 h without propulsion (Type A); the 2013 two-mode trucks allow 28 °C against the inverter module after 360 min key-off (Type B, two trips). Mitsubishi (2023 Outlander PHEV rear motor) compares two coil sensors after 5,400 s soak and sets it at 13 °C difference. P0A32 and P0A33 cover hard circuit faults; P0A35 is only judged while this test passes. Expect a hybrid warning and limited electric drive.

Symptoms

• Hybrid warning light after a cold start
• Motor B temperature differs clearly from other temperatures after a long rest
• Electric drive limited as a precaution

Most likely causes

• Motor B thermistor reading drifted out of tolerance
• Corroded terminals adding resistance in the sensor circuit
• Comparison sensor (inverter, coolant or fluid temperature) is wrong
• Uneven cooling of the drive unit, e.g. low fluid level

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the codes with a hybrid-compatible scanner and write down the freeze frame data
2. Compare the reading with other engine data while varying the engine speed.
3. Make sure the battery cooling air intake is clean
4. Check the 12 V auxiliary battery, which can also trigger warnings
5. Leave any high-voltage measurements to a specialized repair shop

Good to know

• It can trigger limp mode.
• It affects emissions.

What each character of P0A31 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• A: Hybrid or air and fuel
• 31: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0A31?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0A31?

The most common causes are: motor B thermistor reading drifted out of tolerance; corroded terminals adding resistance in the sensor circuit; comparison sensor (inverter, coolant or fluid temperature) is wrong.

Related codes

• P0A30Drive Motor B Temperature Sensor Circuit
• P0A32Drive Motor B Temperature Sensor Circuit Low
• P0A33Drive Motor B Temperature Sensor Circuit High
• P0A35Drive Motor B Over Temperature
• P0A2BDrive Motor A Temperature Sensor A Circuit Range/Performance

Sources

• gsi.ext.gm.com: 11OBDG01 HYBRID Diagnostics
• gsi.ext.gm.com: 13OBDG06 Hybrid Diagnostics
• mitsubishitechinfo.com: N503240970000700USA
• law.cornell.edu: 13 CCR 1968.2

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.