P0A44 – Drive Motor “B” Temperature Sensor Circuit

P0A44 means the ECU has detected a **fault in the Drive Motor “B” temperature sensor circuit**, the sensor responsible for reporting how hot the secondary electric motor (usually the rear motor on AWD hybrids/EVs) becomes during operation. If the signal is missing, unstable, or outside the valid electrical range, the ECU cannot safely monitor rear-motor temperature. To protect high-voltage components, it may disable AWD, reduce torque, or trigger limp mode. This guide explains what P0A44 means, the symptoms, common causes, how to diagnose it, and the repairs that typically solve the problem.

What Does P0A44 Mean?

P0A44 is set when the Hybrid/EV Powertrain Control Module sees a **temperature signal from Drive Motor “B” that is electrically incorrect**, such as an open circuit, short, or invalid sensor voltage. These sensors use NTC thermistors embedded in or near the stator of the rear traction motor. When their resistance/voltage readings fall outside the acceptable limits, the ECU assumes temperature cannot be monitored accurately.

Because rear-motor cooling is essential for AWD function, the ECU often restricts torque or disables Drive Motor “B” completely until the fault is resolved.

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–€450
• Last Updated: 2025-11-24

Real-World Example / Field Notes

P0A44 is common on Toyota/Lexus e-AWD hybrids, Hyundai/Kia dual-motor EVs, and GM/Voltec systems. In a Lexus NX300h, the rear motor temperature stayed stuck at –40°C (open-circuit default), disabling AWD on every start. The culprit was a broken wire where the rear-motor harness rubbed against the subframe. In a Kia EV6, intermittent high readings were caused by coolant intrusion inside the sensor connector, which slowly corroded the terminals until the circuit failed completely.

Symptoms of P0A44

• AWD disabled: Vehicle operates in FWD only.
• Reduced EV power: Rear motor torque is limited or unavailable.
• Incorrect temperature readings: Often fixed at –40°C or 150°C.
• Limp mode: Heavy torque limitations, especially during acceleration.
• Warning messages: “AWD Malfunction,” “EV System Error,” or “Check Hybrid System.”
• Cooling fans running at high speed: ECU attempts to compensate for unknown motor temperature.
• READY-mode issues: Severe faults may affect startup on some platforms.

Common Causes of P0A44

Most Common Causes

• Open circuit in the Drive Motor “B” temperature sensor wiring.
• Failed or open thermistor inside the rear traction motor.
• Corroded sensor connector pins or water intrusion.
• Broken, chafed, or pinched harness near the rear subframe.
• Unseated or disconnected sensor plug.

Less Common Causes

• Internal stator temperature circuit damage inside the motor.
• Short-to-voltage or short-to-ground causing extreme readings.
• Coolant leaks contaminating the temperature connector.
• Hybrid ECU input-driver malfunction (rare).

Diagnosis: Step-by-Step Guide

Your goal is to determine whether the fault lies in the wiring, connector, or sensor inside Drive Motor “B.”

Tools You’ll Need: EV-capable scan tool, multimeter, wiring diagram, IR thermometer, coolant tools, and optionally an oscilloscope.

1. Check live temperature data. A fixed –40°C indicates an open circuit; 150°C+ suggests a short-to-ground.
2. Inspect the connector closely. Look for corrosion, moisture, bent pins, or a loose lock tab.
3. Perform a wiggle test. Watch live data while moving the harness near the rear motor and subframe.
4. Test signal voltage. High voltage indicates an open sensor; low voltage points to a short.
5. Measure sensor resistance. Compare the thermistor’s resistance to spec at ambient temperature.
6. Check continuity between the ECU and motor. Open or high-resistance circuits cause unstable readings.
7. Inspect harness routing. Rear-motor harnesses often rub on brackets, causing intermittent opens.
8. Verify real motor temperature. Use an IR thermometer to confirm actual heat vs displayed values.
9. Check rear inverter cooling performance. Overheating can cause temperature spikes, though it rarely triggers P0A44 alone.
10. Review freeze-frame data to determine whether the fault occurred at startup, under load, or during regen braking.

Pro Tip: If the sensor reads –40°C immediately at key-on and never changes, the circuit is fully open. Start with wiring and connector checks before considering internal motor faults.

Possible Fixes & Repair Costs

• Repair open or damaged wiring: €10–€120.
• Clean or replace corroded connectors: €10–€50.
• Replace Drive Motor “B” temperature sensor (if serviceable): €150–€300.
• Repair internal stator temperature circuit: €300–€500+ (model dependent).
• Fix coolant leaks contaminating the harness: €40–€150.
• Bleed or restore cooling system flow: €40–€120.

Always diagnose wiring and connector integrity first — most P0A44 cases are caused by open circuits or corrosion, not internal motor failures.

Can I Still Drive With P0A44?

Driving is possible but risky. Because the ECU cannot verify rear-motor temperature, it may disable AWD or limit torque at any time. If temperature readings stay at –40°C or if warnings appear, avoid driving and fix the issue promptly to prevent motor overheating or shutdown.

Last updated: January 22, 2026