P0A30
Drive Motor B Temperature Sensor Circuit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- A
- AreaHybrid propulsion
- 30
- FaultThe specific fault in that area
What it means
P0A30 means the hybrid or electric vehicle control unit has detected a fault in the circuit of the temperature sensor for drive motor B (the second traction motor or motor generator). The signal was open, shorted, out of range or implausible compared with expected values, so the motor temperature cannot be trusted. Which physical motor is 'B' depends on the model.
Symptoms
- Hybrid or EV system warning light or malfunction indicator lamp on
- Reduced power or limp mode from the electric drive
- Reduced electric-only driving or reduced regenerative braking
- Cooling fan or pump for the drive system running harder than normal
- Poor fuel economy or reduced range
- In some cases the car will not enter ready mode
Possible causes
- Faulty drive motor B temperature sensor (open, shorted or drifting)likely
- Damaged, chafed or broken wiring between the sensor and the control unitlikely
- Corroded, loose or contaminated connector at the motor, inverter or control unitlikely
- Real motor overheating from a cooling system problem, such as low coolant, a failed pump or a blocked passage, causing an implausible readingpossible
- Fault inside the inverter or motor control unit input circuitrare
- Internal motor or harness fault that cannot be reached without stripping the unit, which varies by modelrare
How to diagnose
- Read all stored and pending codes, and record the freeze frame data. Look for related codes such as other motor temperature, inverter, or cooling system codes.
- Check for manufacturer bulletins or known issues for the specific model and motor layout, as the location of motor B varies.
- Inspect the visible low-voltage wiring and connectors for chafing, heat damage, water ingress, corrosion and bent or pushed-back pins. Do not touch orange high-voltage cabling unless qualified.
- Check coolant level and condition and confirm the drive system cooling pump and fans work, following the model's procedure.
- With the car cold-soaked, compare the live motor B temperature with the other motor temperature, inverter temperature and coolant temperature. A cold reading that is far off or fixed points to the sensor or circuit.
- Have a person trained in high-voltage systems isolate the system, then measure the sensor resistance and compare it with the specification for that model.
- Check the sensor signal and return circuits for open circuit, short to earth, short to supply and high resistance, and check the reference voltage at the control unit.
- Wiggle-test the harness with live data on screen to find an intermittent fault.
How to fix
- Replace the drive motor B temperature sensor if it is out of specification, following the manufacturer's procedure.
- Repair or replace damaged wiring, and clean or replace corroded or damaged connectors and terminals.
- Correct any cooling system fault found, such as topping up and bleeding coolant, or replacing a failed pump or fan.
- Replace or repair the inverter or motor control unit only after the wiring and sensor have been proven good.
- Clear the codes after the repair and road test to confirm the fault does not return.
Can I keep driving?
The car can usually be driven carefully for a short time, but power may be limited and the motor cannot be protected from overheating without a valid temperature signal. Avoid hard or long-distance driving and get it diagnosed soon; stop if a red warning appears or power is lost.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.