Low coolant level or poor flow in the motor and inverter cooling circuit; Failed or weak electric coolant pump for the power electronics and motor circuit; Blocked radiator, restricted airflow or faulty cooling fan; Faulty drive motor B temperature sensor or its wiring and connector, giving a false high reading; Air trapped in the cooling circuit after previous work; Internal motor fault such as winding or bearing damage causing excess heat; Inverter or control unit fault causing excessive motor current.

P0A35

Drive Motor B Over Temperature.

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
A: AreaHybrid propulsion
35: FaultThe specific fault in that area

What it means

P0A35 is the generic code for a Drive Motor 'B' over temperature condition on a hybrid or electric vehicle. The hybrid control unit saw the motor temperature sensor reading, or a calculated motor temperature, rise above the allowed limit. It usually reduces motor output to protect the motor and sets the code. Which motor is 'B' (for example a second traction motor or generator) depends on the model.

Symptoms

Hybrid system or master warning light on
Reduced power or limp mode, with limited acceleration
Electric assist reduced or unavailable, with the engine doing more work
Cooling fan or pump running loudly or constantly
Poor performance on hills or when towing
Hybrid system may shut down in severe cases

Possible causes

Low coolant level or poor flow in the motor and inverter cooling circuitlikely
Failed or weak electric coolant pump for the power electronics and motor circuitlikely
Blocked radiator, restricted airflow or faulty cooling fanpossible
Faulty drive motor B temperature sensor or its wiring and connector, giving a false high readingpossible
Air trapped in the cooling circuit after previous workpossible
Internal motor fault such as winding or bearing damage causing excess heatrare
Inverter or control unit fault causing excessive motor currentrare

How to diagnose

Read all stored codes and freeze frame data, noting motor temperature, vehicle speed, load and ambient temperature when the code set
Check for other hybrid, inverter, cooling or temperature sensor codes, as they point towards the cause
With the system cool, check the coolant level and condition in the hybrid or inverter circuit, following the manufacturer's procedure for that model
Inspect the radiator, grilles and cooling fans for blockage, damage or failure, and check the fan operates when commanded
Check the electric coolant pump runs and that coolant is flowing, using live data or a command test where supported
Inspect the motor temperature sensor wiring and connectors for damage, corrosion or heat marks
Compare the motor temperature reading with other temperature sensors on a cold system to spot a sensor fault
Only if the above is clear, test the motor and inverter as per manufacturer procedures, using high voltage safe working practice

How to fix

Top up or replace coolant to the correct specification and bleed the circuit as per the manufacturer's procedure
Replace a faulty electric coolant pump
Clear blockages from the radiator and airflow path, and repair or replace faulty cooling fans
Repair damaged wiring or connectors, or replace a faulty motor temperature sensor
Repair or replace the drive motor or inverter if testing confirms an internal fault, using a qualified high voltage technician

Can I keep driving?

High severity

Avoid driving, or limit it to a short, gentle trip to a workshop, as overheating can damage the motor and the car may shut down. Do not carry on if the warning stays on or power is reduced.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.