P0A07 means the ECU has detected a **low circuit voltage** condition in the Drive Motor “A” Temperature Sensor — the sensor responsible for monitoring the temperature of the main electric drive motor in a hybrid or fully electric vehicle. A “circuit low” fault usually indicates the ECU is seeing a voltage that’s too low to be realistic, often caused by a short-to-ground, internal sensor failure, or coolant/oil contamination in the connector. When this happens, the system may limit electric drive power or activate protection mode. This guide explains the meaning of P0A07, symptoms, causes, diagnostic steps, and the proven fixes that resolve this temperature-sensor fault.
What Does P0A07 Mean?
P0A07 sets when the ECU detects that the Drive Motor “A” Temperature Sensor signal voltage is **below the expected range**. Most drive motor temperature sensors use an NTC thermistor — as temperature rises, resistance drops, causing voltage to fall in a predictable pattern. When the voltage drops too low, the ECU interprets the reading as a fault rather than a true temperature, typically caused by a shorted circuit or an internally damaged sensor.
Because motor temperature is critical for torque output and thermal protection, the ECU may reduce electric drive performance or activate fail-safe modes to protect the motor windings and inverter.
Quick Reference
- OBD-II Family: P-Code (Hybrid/EV Powertrain)
- Scope: Generic
- System: Drive Motor Temperature Monitoring
- Difficulty Level: Moderate
- Estimated Repair Cost: €80–€300
- Last Updated: 2025-11-24
Real-World Example / Field Notes
P0A07 shows up frequently on Toyota Prius, Lexus hybrids, Hyundai/Kia hybrids, Nissan Leaf, and Chevrolet Volt. In one Volt case, the temperature reading stayed locked at 140–150°C at startup — a clear sign of a short-to-ground in the motor temperature circuit. The cause was coolant seepage into the connector, which bridged the signal pin. Cleaning the connector and fixing a hairline crack in the coolant hose above the harness restored normal operation. On Nissan EV models, road-spray corrosion near the subframe wiring is a common trigger.
Symptoms of P0A07
- Reduced electric drive power: ECU lowers torque output.
- Limp mode: Hybrid system may force engine-only operation.
- Warning messages: “Motor Overheating,” “EV System Error,” or “Check Hybrid System.”
- Cooling fan running excessively: ECU reacts to falsely high temperature readings.
- Poor acceleration: Electric assist may be limited or disabled.
- Unrealistic temperature readings: Often extremely high values.
- Check Engine Light: P0A07 commonly appears with inverter and motor control codes.
Common Causes of P0A07
Most Common Causes
- Short-to-ground in the temperature sensor wiring.
- Failed or internally shorted Drive Motor “A” temperature sensor.
- Coolant or oil contamination inside the connector.
- Corroded or water-damaged connector pins.
- Damaged wiring harness near the motor housing.
Less Common Causes
- Actual motor overheating creating abnormal resistance values.
- Low coolant or blocked cooling passages (liquid-cooled motors).
- ECU internal signal-processing error (rare).
- Improper coolant type affecting temperature response.
- Sensor mounting failure causing poor thermal contact.
Diagnosis: Step-by-Step Guide
Your goal is to confirm whether the low voltage is due to wiring damage, contamination, or internal sensor failure.
Tools You’ll Need: Hybrid/EV-capable scan tool, multimeter, IR thermometer, wiring diagram, coolant testing tools, and basic hand tools.
- Check live motor temperature data. Unrealistically high readings (120°C+) at startup indicate a short-to-ground.
- Inspect the connector for contamination. Coolant or oil can easily bridge the signal pin and lower voltage.
- Perform a wiggle test. Move the harness while watching live data — any jumps indicate wiring issues.
- Check wiring for insulation damage. Look for cuts, abrasion, or melted sections near the motor.
- Measure sensor resistance. Compare values to OEM specs; very low resistance usually means internal failure.
- Test for short-to-ground. Unplug the sensor and check continuity from signal pin to chassis ground.
- Compare scanner reading to IR thermometer. If IR temperature is normal but live data shows overheating, the signal is shorted.
- Inspect motor cooling system (if applicable). Low coolant or air pockets can create real temperature swings.
- Look for related codes. P0A2F or P0A94 indicate broader cooling or inverter issues.
- Check sensor physical mounting. Loose or damaged housings can affect heat transfer and resistance readings.
Pro Tip: If live data shows a fixed high temperature regardless of driving conditions or IR readings, the circuit is almost certainly shorted to ground or the sensor’s internal thermistor has failed.
Possible Fixes & Repair Costs
- Repair shorted wiring: €10–€80.
- Clean or replace contaminated connector: €10–€40.
- Replace Drive Motor “A” Temperature Sensor: €80–€200.
- Fix coolant leaks near the connector or harness: €20–€120.
- Bleed motor cooling system (if applicable): €40–€120.
- Replace coolant pump (liquid-cooled motors): €100–€350.
Most P0A07 issues originate from wiring faults or contamination inside the connector, so inspect these areas thoroughly before replacing the sensor.
Can I Still Drive With P0A07?
Driving with P0A07 is risky. The ECU may falsely believe the motor is overheating and reduce or disable electric drive, causing sudden loss of power. If the issue is a real overheating condition, further driving could damage the motor windings. Only drive short distances and repair the fault as soon as possible.
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
- P0A07 indicates a low-voltage condition in the Drive Motor “A” Temperature Sensor circuit.
- Most causes involve wiring damage, contamination, or a shorted sensor.
- Driving may be possible but risks sudden power loss or motor overheating.
- Live data and resistance testing are key for accurate diagnosis.
FAQ
What causes P0A07 most often?
Short-to-ground wiring faults and connector contamination are the most common causes of abnormally low sensor voltage.
Is P0A07 serious?
Yes — if the ECU believes the motor is overheating, it will limit or disable electric drive to prevent damage.
Why does the temperature reading look extremely high?
A low circuit voltage mimics the behavior of an extremely hot motor in an NTC thermistor system, triggering protection mode.
Can coolant contamination cause P0A07?
Absolutely — coolant is conductive enough to partially short the sensor circuit and drive voltage below expected levels.
How do I fix P0A07?
Inspect and clean connectors, repair shorted wiring, check cooling system integrity, and replace the temperature sensor if readings remain incorrect.