P0A46

What it means

P0A46 means the hybrid or electric vehicle control unit has found the signal from the position sensor on drive motor 'B' to be implausible or outside its expected range. The sensor, usually a resolver or similar rotor position sensor, tells the inverter exactly where the rotor is so it can time the motor current. The code sets when the reported position or speed does not agree with expected values, such as when it conflicts with other motor data or shows impossible jumps. Which motor is 'B' and how the sensor is built depends on the model and drivetrain layout.

Symptoms

• Hybrid or EV system warning light, or master warning light, on the dashboard
• Reduced power or limp mode
• Rough, jerky or hesitant drive-away or acceleration
• Engine starting more often, or the car refusing to go into ready or drive mode
• Unusual whine or noise from the motor or transaxle area
• Loss of electric drive or regenerative braking feel

Possible causes

• Damaged, chafed or corroded wiring or connector in the motor position sensor circuit, giving a noisy or distorted signallikely
• Faulty motor position sensor (resolver) or sensor out of position or loose after work on the motorlikely
• Electrical interference or a poor shield or earth connection on the sensor signal wirespossible
• Fault inside the inverter or motor control unit that processes the sensor signalpossible
• Mechanical problem in the motor or transaxle, such as rotor or bearing damage, affecting the sensor readingrare
• Outdated or faulty control unit software, where the manufacturer has issued a fix for this faultrare

How to diagnose

1. Follow the manufacturer's high voltage safety procedure first. Only a technician trained in hybrid and EV systems should work on the high voltage system.
2. Read all stored codes and freeze frame data, and note any other motor, inverter or position sensor codes.
3. Check for technical service bulletins or software updates for this code on the specific model.
4. Inspect the sensor wiring, connectors and shielding for chafing, water ingress, corrosion, bent pins or poor retention, and check for recent repairs nearby.
5. With the system safely isolated, test the sensor circuit resistance, continuity and insulation against the manufacturer's specification.
6. With a scan tool, compare live motor position and speed data against other speed data for plausibility, including during a road test.
7. Check the sensor mounting and alignment, and look for signs of mechanical damage or contamination at the motor.
8. If wiring and sensor test fine, check the inverter or control unit power supplies and earths before suspecting the unit itself.

How to fix

• Repair or replace damaged wiring, connectors or shielding, and restore proper earth connections
• Replace the faulty motor position sensor or resolver, or correct its mounting, following the manufacturer's procedure
• Replace or repair the inverter or motor control unit if it is confirmed faulty
• Repair the motor or transaxle if mechanical damage is found
• Update the control unit software if an applicable update exists for this known issue
• Clear the code after repair and road test to confirm it does not return

Can I keep driving?

Nearby codes

• P0A45GenericDrive Motor B Position Sensor Circuit
• P0A47GenericDrive Motor B Position Sensor Circuit Low