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DTC codes / P0Exx · Hybrid propulsion / P0E28

P0E28Drive Motor Inverter Temperature Sensor H Circuit

P0E28 indicates that the powertrain control module has detected an abnormal condition in the electrical circuit for the 'H' temperature sensor that monitors the drive motor inverter, which is the component that converts direct current to alternating current for the electric motor. The computer compares the sensor's signal to expected values and sets this code when the voltage or resistance falls outside the normal range, often due to a wiring fault or sensor failure.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the check engine light or service vehicle soon message, often with no other noticeable symptoms.
  • Reduced power output or a limp mode that limits vehicle speed to protect the inverter from overheating.
  • Inconsistent or erratic temperature readings on a scan tool data stream for the inverter sensor.
  • Possible shutdown of the electric drive system if the fault is severe, leading to a no-start or stalled condition.
  • In rare cases, a burning smell or visible damage near the inverter if the sensor circuit has shorted.
  • Often no symptoms besides the warning light, especially in early stages of the fault.

Common causes, most likely first

  1. Damaged or corroded wiring harness or connector at the inverter temperature sensor H circuit.
  2. Failed temperature sensor H inside the inverter assembly.
  3. Open or short circuit in the sensor signal or ground circuit due to chafed wires or loose pins.
  4. Faulty powertrain control module or inverter control module not properly reading the sensor signal.
  5. Moisture intrusion or contamination in the connector causing intermittent signal.
  6. Heat damage to the sensor or wiring from prolonged high-load operation.
  7. Aftermarket accessories or improper previous repairs that disturbed the sensor circuit.

How to diagnose and fix it

  1. Use a scan tool to retrieve the code and view live data for the inverter temperature sensor H to confirm the signal is abnormal.
  2. Visually inspect the sensor connector and wiring for corrosion, loose pins, or physical damage, and repair as needed.
  3. Perform a resistance and voltage drop test on the sensor circuit according to the manufacturer's specifications to isolate an open or short.
  4. Check the sensor's resistance at known temperatures and compare to the expected curve to determine if the sensor itself has failed.
  5. If the sensor is faulty, replace the inverter temperature sensor or the affected inverter assembly as required by the vehicle design.
  6. Clear the code and perform a road test to verify the repair, ensuring the live data now reads within normal range.
  7. If the code persists after sensor and wiring repairs, diagnose the control module or consult a dealer for advanced diagnostics.

Common misdiagnosis traps for P0E28

  • A loose or corroded connector pin is frequently the real culprit, so always inspect and clean the connector before condemning the sensor or inverter.
  • The code can be set by a momentary glitch from low battery voltage, so check the 12-volt battery and charging system before replacing expensive components.
  • Some vehicles use a shared ground for multiple sensors, and a bad ground can cause this code along with others, so check ground points thoroughly.
  • After a collision or undercarriage damage, the wiring harness to the inverter may be pinched even if the sensor itself tests good.
  • Replacing the inverter without first verifying the sensor circuit can lead to a repeat failure if the original wiring fault remains.

Can I keep driving with P0E28?

It is generally safe to drive with this code if the vehicle is not in limp mode and the temperature gauge reads normally, but avoid heavy acceleration or sustained high speeds that could overheat the inverter. If the vehicle enters limp mode or shows a high temperature warning, stop driving and seek service immediately to prevent damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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