Fault code P0A97 – hybrid battery pack cooling fan 2 performance/stuck off

Fault code P0A97 is called “Hybrid Battery Pack Cooling Fan 2 Performance/Stuck Off” 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 P0A97

The P0A97 fault code is intended to be displayed exclusively on hybrid vehicles. Indicates that the Powertrain Control Module (PCM) has detected the battery cooling fan of the hybrid unit hanging up when the unit is off. Refers to cooling fan #2.

Fault code P0A97 – hybrid battery pack cooling fan 2 performance/stuck off

The high voltage battery pack is controlled by the Hybrid Vehicle Battery Management System (HVBMS). Which also communicates with the PCM and other controllers. Battery temperature, cell resistance, charge level, and overall status are among the functions monitored and calculated by the HVBMS.

The HVBMS uses temperature sensors to determine how hot the hybrid vehicle’s battery is. Based on these results, the cooling fans are controlled. Thus, the fans are started when the temperature of the battery pack rises to a predetermined level.

The fan speed is controlled by a relay. The power control module, sends command signals to the battery cooling fan unit. To get the fan speed corresponding to the battery temperature of the hybrid vehicle.

If the HVBMS sends an input signal to the PCM that indicates that the battery cooling fan is hovering in the off state. Then code P0A97 will be stored, and the malfunction light may illuminate.

For most vehicles it will take several failure cycles before the MIL will illuminate.

Symptoms of vehicle malfunctions

The main signal that an error P0A97 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 illuminate (the code will be stored as a fault).
  2. Other high voltage battery related codes may be present.
  3. Reduced vehicle performance.
  4. Increased fuel consumption.
  5. Deactivation of the electric motor unit.

The severity of code P0A97 is high, as there is a risk of excessive high voltage battery temperature rise when the fan is not working. This in turn will result in deactivation of the electric propulsion system.

Factors that can cause this error code

The error code P0A97 can mean that one or more of the following problems have occurred:

  • The high voltage battery fan has failed.
  • Fan relay has failed.
  • Corrosion, loose or broken electrical wiring and connections.
  • Faulty cooling fan module.
  • Faulty HVBMS sensor.
  • Vehicle’s 12-volt battery is not delivering the correct voltage.
  • Sometimes faulty PCM module is the cause.

How to fix or reset OBD-2 code P0A97

Some suggested steps for troubleshooting and fix the error code P0A97:

  1. Connect an OBD-II scanner to the vehicle’s diagnostic connector and read all stored data and error codes.
  2. Clear the error codes from the computer memory and test-drive the vehicle to see if the P0A97 code appears again.
  3. If the error code appears again, visually inspect the electrical wires and connectors to the cooling fan.
  4. If necessary, repair or replace any shorted, broken, damaged, or corroded components.
  5. Test the high voltage battery fan.
  6. Check the operation of the high voltage battery temperature sensor.
  7. Check the fan control relay and replace it if necessary.
  8. Test the battery and make sure the system voltage is normal.
  9. If problem persists, check and replace engine control module (ECM) if necessary.

Diagnose and repair of problems

The first step in the P0A97 troubleshooting process is to review the Technical Service Bulletins (TSB). For known problems with a particular vehicle.

The advanced diagnostic steps are very vehicle specific. They may require, special equipment and knowledge to accurately perform the steps.

Visual inspection

Perform a visual inspection, look at the fan and make sure it is fully functional. Rotate the fan by hand, if it does not spin, there is most likely a problem with the bearings, they should be replaced.

Check the electrical connection of the fan. Disconnect the connector and inspect it for corrosion or bent contacts. Repair if necessary and apply dielectric grease to terminals.

Open the fuse box and inspect the cooling fan relay fuses. If they are OK, remove the cooling fan relay and test it. The bottom of the fuse box cover usually indicates the location.

Use an ohmmeter to check for continuity between the relay terminal on the fan side and the connector on the fan. If there is a signal, then the fan is defective. Otherwise the harness between the fuse box and the blower is faulty.

Check the high voltage battery temperature sensor with an ohmmeter. Remove the connector, set the ohmmeter to the 200000 scale. Also check the sensor terminals.

If these steps failed to find the fault, there may be a bad connection to the PCM or the PCM itself is faulty. If this is the case, it is best to consult a specialist for reprogramming or replacing the control unit.

On which vehicles does this problem occur most frequently

Fault code P0A97 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Ford
  • Toyota

Fault code P0A97 can sometimes be found with other errors. The most common are the following: P0A96, P0A98, P0A99, P0A9A.


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