P0A47 means the ECU has detected a **high-voltage condition in the Drive Motor “B” temperature sensor circuit**, which monitors how hot the secondary or rear traction motor gets in dual-motor hybrids and EVs. “Circuit High” indicates the sensor signal voltage is above the valid operating range — typically due to an open circuit, unplugged connector, broken wiring, or a failed thermistor inside the motor. When the ECU loses the ability to monitor rear-motor temperature, it disables AWD, limits torque, or triggers limp mode to prevent overheating. This guide explains what P0A47 means, the causes, symptoms, diagnosis steps, and the most common repair solutions.
What Does P0A47 Mean?
P0A47 is triggered when the Hybrid/EV Powertrain Control Module sees **voltage from the Drive Motor “B” temperature sensor that is too high**, meaning the ECU believes the motor is colder than physically possible. NTC thermistors (used in these sensors) generate higher voltage at colder temperatures. When the circuit is open, the ECU interprets the sensor as reading extremely low temperatures — commonly around –40°C.
Because accurate rear-motor temperature is essential for AWD operation, the ECU immediately restricts torque or shuts down Drive Motor B until the fault is corrected.
Quick Reference
- OBD-II Family: P-Code (Hybrid/EV Powertrain)
- Scope: Generic
- System: Drive Motor “B” Temperature Monitoring
- Difficulty Level: Moderate
- Estimated Repair Cost: €120–€420
- Last Updated: 2025-11-24
Real-World Example / Field Notes
This code is common on Toyota/Lexus e-AWD hybrids, Hyundai/Kia EVs, Volvo PHEVs, and GM/Voltec dual-motor setups. In a Toyota NX300h, the rear motor showed a steady –40°C reading from startup. A broken signal wire inside the underbody harness was the cause. On a Kia EV6, P0A47 appeared intermittently due to a partially unplugged connector caused by road splash and vibration. In both cases, once the circuit was restored, AWD and torque returned immediately.
Symptoms of P0A47
- AWD disabled: Vehicle operates in FWD only.
- Fixed low temperature reading: Commonly –40°C at all times.
- Reduced EV torque: Rear motor may not engage under load.
- Limp mode activation: Noticeable power loss during acceleration.
- System warnings: “AWD Malfunction,” “Check Hybrid System,” or “EV System Error.”
- Cooling fans/pump running aggressively: ECU compensates for unknown temperature.
- Possible READY-mode issues: Severe faults may affect EV startup reliability.
Common Causes of P0A47
Most Common Causes
- Open circuit in the Drive Motor “B” temperature sensor wiring.
- Broken or disconnected sensor connector.
- Failed thermistor inside the rear motor (open resistance).
- Corroded or oxidized connector terminals.
- Harness damage along the subframe or underbody routing.
Less Common Causes
- Coolant intrusion causing intermittent opens.
- Internal stator temperature-sense circuit failure.
- High-resistance wiring segment from corrosion or pin fatigue.
- ECU input-driver fault (rare but possible).
Diagnosis: Step-by-Step Guide
Your goal is to identify where the open circuit occurs — at the connector, wiring, or internal motor temperature sensor.
Tools You’ll Need: EV-safe scan tool, multimeter, wiring diagram, IR thermometer, coolant-handling tools.
- Check live data. A steady –40°C reading confirms an open sensor circuit.
- Inspect the connector. Look for corrosion, bent pins, moisture intrusion, or loose locking tabs.
- Wiggle-test the harness. Watch live data while gently moving the wiring — fluctuations confirm broken conductors.
- Measure signal voltage. High voltage with the sensor connected indicates an internal open.
- Test sensor resistance. Infinite resistance at ambient temperature confirms thermistor failure.
- Check continuity from sensor to ECU. Open or high-resistance paths show where the problem lies.
- Inspect underbody harness routing. Look for compression, abrasion, or bracket contact.
- Verify real motor temperature. Use an IR thermometer to confirm that the motor is not actually cold.
- Check cooling system performance. Though not the root cause, overheating may accompany sensor failures.
- Review freeze-frame data. Immediate appearance at key-on almost always indicates an open circuit.
Pro Tip: If Drive Motor “B” temperature reads –40°C immediately at READY-mode and never changes, suspect an open signal wire or failed thermistor long before considering ECU or motor replacement.
Possible Fixes & Repair Costs
- Repair broken or open wiring: €20–€120.
- Clean or replace corroded connectors: €10–€50.
- Replace Drive Motor “B” temperature sensor (if replaceable): €150–€250.
- Repair internal motor temperature circuit: €300–€500+ depending on vehicle.
- Fix coolant leaks at the connector area: €40–€150.
- Bleed/restore cooling flow: €40–€120.
Because “circuit high” almost always indicates an open, always inspect wiring and connectors thoroughly before replacing expensive components.
Can I Still Drive With P0A47?
Driving is possible, but AWD or rear EV torque may cut out at any time. Since the ECU cannot monitor real temperature, it may reduce power unexpectedly or prevent EV operation. Avoid long trips or high-load driving until the fault is repaired.
Related Codes
- P0A6C – Hybrid Battery Voltage System Isolation Sensor Range/Performance
- P0A9F – Hybrid Battery Temperature Sensor Too Hot
- P0A9E – Hybrid Battery Temperature Sensor Too Cold
- P0A9D – Hybrid Battery Temperature Sensor Range/Performance
- P0A9C – Motor Electronics Coolant Temperature Sensor Circuit High
- P0A9B – Motor Electronics Coolant Temperature Sensor Circuit Low
- P0A9A – Motor Electronics Coolant Temperature Sensor Circuit Range/Performance
- P0A99 – Motor Electronics Coolant Temperature Sensor Circuit
- P0A98 – Hybrid Battery Pack Cooling Fan 2 Performance
- P0A97 – Hybrid Battery Pack Cooling Fan 2 Control Circuit
Key Takeaways
- P0A47 indicates a high-voltage (open-circuit) fault in the rear-motor temperature sensor circuit.
- Broken wiring, unplugged connectors, and failed thermistors are the most common causes.
- AWD may disable itself, and torque reduction is likely.
- A constant –40°C reading is the fastest diagnostic clue.
FAQ
What causes P0A47 most often?
An open circuit — usually a disconnected connector, broken wire, or failed thermistor inside the motor.
Why does the temperature read –40°C?
–40°C is the default reading when the ECU detects no resistance signal from the temperature sensor, indicating an open circuit.
Is P0A47 dangerous?
Yes. The ECU may disable AWD or drastically reduce torque, and real overheating may go unnoticed if the sensor is not working.
How do I diagnose P0A47?
Check live data, inspect connectors, test resistance and signal voltage, and verify wiring continuity between the motor and ECU.
Can I drive with P0A47?
Short trips might be possible, but sudden power loss or AWD shutdown can occur. Repair the circuit before continuing normal driving.