Fault code P0A0D – high voltage system interlock circuit high

Fault code P0A0D is called “High Voltage System Interlock Circuit High” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0A0D

The P0A0D fault code is intended to be displayed exclusively on hybrid vehicles. Indicates that the Powertrain Control Module (PCM) has detected a high signal level in the high voltage interlock circuit.

Fault code P0A0D – high voltage system interlock circuit high

The high voltage system of the hybrid vehicle is equipped with several safety devices. These are designed to reduce the risk of electric shock during repair work on the vehicle or in the event of an accident.

If the Power Control Module (PCM) detects that any of the safety devices are disconnected or not connected, the hybrid system will shut down. When the PCM detects that the hybrid system is disabled, it sets the code P0A0D.

This problem is an electrical malfunction and is most often caused by poorly inserted connectors or a “check” of the high voltage battery, after repairs have been made.

Symptoms of vehicle malfunctions

The main signal that an error P0A0D has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
  2. The high voltage system may not work.
  3. In many cases, the vehicle will not work at all.

The P0A0D error is quite serious, as it can cause problems in the electrical system. It may also affect the full functionality of the vehicle.

Factors that can cause this error code

The error code P0A0D can mean that one or more of the following problems have occurred:

  • Loose or shorted high voltage interlock harness.
  • Service disconnect plug not properly connected (check).
  • Failure of high voltage protection device.
  • Failure of inverter.
  • Malfunction of the power control module.
  • Power module software is executing with an error and needs to be updated.
  • Sometimes the cause is a faulty PCM module.

How to fix or reset OBD-2 code P0A0D

Some suggested steps for troubleshooting and fix the error code P0A0D:

  1. Inspect the wires and connection connectors for damage.
  2. Check if the service disconnect plug is properly connected.
  3. Check the inverter.
  4. Inspect fuses, replace blown ones.
  5. If error persists, check PCM module.

Diagnose and repair of problems

The first step in the P0A0D troubleshooting process is to review the Technical Service Bulletins (TSB). Check for known problems with your particular vehicle.

If any repairs have been made and connectors have been disconnected prior to the occurrence of the error, they should be checked. The high voltage battery service disconnect plug should also be looked at.

Further troubleshooting should continue with a visual inspection of the wires for possible damage or malfunctions. Any possible damage should be repaired immediately.

If the P0A0D error remains after these steps, the best option is to contact a specialized service center. As further steps require special knowledge for troubleshooting.

Sometimes it is possible that the PCM has failed or there is a problem with the software. In this case it is necessary to replace and reprogram PCM, which is difficult to do without special knowledge.

On which vehicles does this problem occur most frequently

Fault code P0A0D can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Hyundai
  • Kia (Niro, Optima)
  • Lexus (CT 200h, RX400h, RX450h)
  • Toyota (Alphard, Aqua, Auris, Camry, Prius)

Fault code P0A0D can sometimes be found with other errors. The most common are the following: P0A0A, P0A0B, P0A0C, P0A0E.


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