P0A34 Drive Motor “B” Temperature Sensor Circuit Intermittent

P0A34 Possible Causes

  • Faulty hybrid vehicle motor
  • Hybrid vehicle motor wiring harness is open or short-circuited
  • Poor electrical connection in the hybrid vehicle motor circuit

What Does It Mean?

How to Fix Code P0A34

Check the “Possible Causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A34 Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P0A34 Meaning

The Engine Control Module (ECM) monitors the “B” drive motor temperature sensor. The ECM sets the OBDII code when the “B” drive motor temperature sensor does not meet factory specifications.

P0A35 Drive Motor “B” Overheating

P0A35 Possible Causes

  • Faulty hybrid vehicle engine
  • Hybrid vehicle engine wiring harness is open or shorted
  • Poor electrical connection in hybrid vehicle engine circuit

What Does It Mean?

How to Fix Code P0A35

Check the “possible causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A35 Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P0A35 Meaning

The engine control module (ECM) monitors the drive motor temperature sensor “B”. The ECM sets the OBDII code when the drive motor temperature sensor “B” does not meet factory specifications.

P0A36 Generator Temperature Sensor Circuit

P0A36 Possible Causes

  • Faulty hybrid vehicle motor
  • Hybrid vehicle motor wiring harness open or shorted
  • Poor electrical connection in hybrid vehicle motor circuit

What Does It Mean?

How to Fix Code P0A36

Check the “Possible Causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A36 Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P0A36 Meaning

Engine temperature sensor #2 detects the transmission-differential fluid temperature. The resistance of the thermistor installed in engine temperature sensor #2 varies with changes in transmission-differential fluid temperature. The construction of engine temperature sensor #2 and how it connects to the HV control ECU are the same as those of engine temperature sensor #1.
Based on the signal provided by engine temperature sensor #2, the HV control ECU limits the load to prevent engine overheating. Additionally, the HV control ECU checks engine temperature sensor #2 for wiring malfunctions and sensor malfunctions.

P0A37 Generator Temperature Sensor Circuit Range / Performance

P0A37 Possible Causes

  • Faulty hybrid vehicle engine
  • Hybrid vehicle engine wiring harness open or shorted
  • Poor electrical connection in hybrid vehicle engine circuit

What Does It Mean?

How to Fix Code P0A37

Check the “Possible Causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A37 Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P0A37 Meaning

Engine temperature sensor No. 2 detects the transmission-differential fluid temperature. The resistance of the thermistor installed in engine temperature sensor No. 2 varies with changes in transmission-differential fluid temperature. The construction of engine temperature sensor No. 2 and how it connects to the HV control ECU are the same as those of engine temperature sensor No. 1.
Based on the signal provided by engine temperature sensor No. 2, the HV control ECU limits the load to prevent engine overheating. Additionally, the HV control ECU checks engine temperature sensor No. 2 for wiring malfunction and the sensor for malfunction.

P0A38 Low Generator Temperature Sensor Circuit

P0A38 Possible Causes

  • Faulty hybrid vehicle motor
  • Hybrid vehicle motor wiring harness open or shorted
  • Poor electrical connection in hybrid vehicle motor circuit

What Does It Mean?

How to Fix Code P0A38

Check the “Possible Causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A38 Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P0A38 Meaning

Engine temperature sensor No. 2 detects the transmission-differential fluid temperature. The resistance of the thermistor installed in engine temperature sensor No. 2 varies with changes in transmission-differential fluid temperature. The construction of engine temperature sensor No. 2 and how it connects to the HV control ECU are the same as those of engine temperature sensor No. 1.
Based on the signal from engine temperature sensor No. 2, the HV control ECU limits the load to prevent engine overheating. Additionally, the HV control ECU checks engine temperature sensor No. 2 for wiring malfunction and the sensor for malfunction.

P0A39 High Generator Temperature Sensor Circuit

Code Meaning

P0A39 indicates a problem with the hybrid engine’s temperature sensor #2, which monitors the temperature of the transaxle fluid. This sensor uses a thermistor: its electrical resistance varies with the fluid temperature. The hybrid (HV) ECU uses this data to:

  • Limit engine load and prevent overheating.

  • Detect sensor or wiring malfunctions.

Note: Its operation is identical to temperature sensor #1, but it is dedicated to the transaxle.

Visible Symptoms

  • 🔥 Check engine light on (or “Service hybrid system soon” message).

  • No other obvious engine symptoms (the system automatically limits performance to protect the engine).

Probable Causes

Priority Cause Description
1 Electrical Issues Open/short-circuited wiring harness, oxidized/faulty connectors, bent/broken pins.
2 Sensor Failure Thermistor out of specifications (incorrect resistance).
3 HV ECU Failure Rare – check after eliminating other causes.
4 Faulty Hybrid Engine Very unlikely (the code specifically targets the sensor circuit).

Diagnostic Procedure

Required Tools: Digital multimeter, OBD2 scanner, vehicle technical documentation.

  1. Visual Inspection (80% of solutions):

    • Check the sensor wiring harness (physical damage, rodent bites).

    • Inspect the connectors:

      • Bent, broken, or corroded pins.

      • Loose connection or moisture.

      • Clean with contact spray if necessary.

  2. Sensor Electrical Test:

    • Disconnect the connector and measure the resistance between the pins:

      • Expected Value: Varies with temperature (refer to manufacturer documentation).

      • Anomaly: Infinite resistance (open circuit) or zero (short circuit).

  3. Circuit Test to HV ECU:

    • Use the multimeter in continuity mode:

      • Check for no break between the sensor and the ECU.

    • Measure the supply voltage (usually 5V) with the ignition on.

  4. ECU Diagnostic:

    • If the wiring and sensor are intact, suspect an HV ECU failure (use a scanner to check live data).

Common Repairs

  • 🔧 Replacement of temperature sensor #2 (moderate cost).

  • 🔧 Repair of wiring harness/connector (soldering, plug replacement).

  • 💡 Tip: After repair, clear the code and test the vehicle under real conditions (temperature rise).

⚠️ Hybrid Safety: Always shut off the high voltage (follow manufacturer procedures) before any intervention.

Why This Approach?

  • Electrical causes (wiring, connectors) account for 90% of P0A39 cases.

  • The sensor is inexpensive and easy to test – replacing it is a quick solution if resistance values are inconsistent.

  • The ECU or hybrid engine is rarely at fault (replace only as a last resort).

Source: Manufacturer technical data (Toyota/Lexus, Honda, Ford Hybrid).

P0A3A Generator Temperature Sensor Circuit Intermittent

P0A3A Possible Causes

  • Faulty hybrid vehicle engine
  • Hybrid vehicle engine wiring harness open or shorted
  • Poor electrical connection in hybrid vehicle engine circuit

What Does It Mean?

How to Fix Code P0A3A

Check the “possible causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A3A Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P0A3A Meaning

Engine temperature sensor No. 2 detects the transmission-differential fluid temperature. The resistance of the thermistor installed in engine temperature sensor No. 2 varies with changes in transmission-differential fluid temperature. The construction of engine temperature sensor No. 2 and how it connects to the HV control ECU are the same as those of engine temperature sensor No. 1.
Based on the signal provided by engine temperature sensor No. 2, the HV control ECU limits the load to prevent engine overheating. Additionally, the HV control ECU checks engine temperature sensor No. 2 for wiring malfunction and the sensor for malfunction.

P0A3B Generator Overheating

P0A3B Possible Causes

  • Faulty hybrid vehicle engine
  • Hybrid vehicle engine wiring harness open or shorted
  • Poor electrical connection of hybrid vehicle engine circuit

What Does It Mean?

How to Fix P0A3B Code

Check the “possible causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A3B Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P0A3B Meaning

Engine temperature sensor No. 2 detects the transmission-differential fluid temperature. The resistance of the thermistor installed in engine temperature sensor No. 2 varies with changes in transmission-differential fluid temperature. The construction of engine temperature sensor No. 2 and how it is connected to the HV control ECU are the same as those of engine temperature sensor No. 1.
Based on the signal provided by engine temperature sensor No. 2, the HV control ECU limits the load to prevent engine overheating. Additionally, the HV control ECU checks engine temperature sensor No. 2 for wiring malfunction and the sensor for malfunction.

P0A3C Drive Motor “A” Temperature Sensor

P0A3C Possible Causes

  •     Faulty drive motor ‘A’ inverter sensor
  •     Drive motor ‘A’ inverter sensor harness is open or shorted
  •     Poor electrical connection in drive motor A inverter sensor circuit

What Does It Mean?

How to Fix Code P0A3C

    Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A3C Possible Symptoms

    Engine light on (or service engine soon warning light)

P0A3C Meaning

The Engine Control Module (ECM) monitors the drive motor ‘A’ inverter overheat sensor. The ECM sets the OBDII code when the drive motor ‘A’ inverter overheat sensor does not meet factory specifications.

P0A3D Drive Motor Inverter Temperature “B

P0A3D Possible Causes

  • Faulty drive motor ‘A’ inverter sensor
  • Drive motor ‘A’ inverter sensor harness is open or shorted
  • Poor electrical connection in drive motor A inverter sensor circuit

What Does It Mean?

How to Fix Code P0A3D

Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P0A3D Possible Symptoms

Engine light on (or service engine soon warning light)

P0A3D Meaning

The Engine Control Module (ECM) monitors the drive motor ‘A’ inverter overheat sensor. The ECM sets the OBDII code when the drive motor ‘A’ inverter overheat sensor does not meet factory specifications.