P0AF9 - OBD II Trouble Code

January 31, 2017

Our automotive experts have put together the following information about the P0AF9 diagnostic trouble code. We've provided the common symptoms that occur when this code is set along with the frequent repairs that address the issues related to the P0AF9 code.

OBD II Fault Code

  • OBD II P0AF9

OBD-II Code High voltage system may not operate is defined as a Hybrid Battery System Voltage Unstable

The hybrid battery pack is composed of many individual battery cells (sometimes over 300 cells). The Hybrid Powertrain Control Module monitors the total voltage output of the hybrid battery pack. If the total output from the battery pack is lower than what it should be, code P0AF9 will set.The High Voltage System may not function.

High voltage system may not operate Symptoms

  • High voltage system may not operate
  • Vehicle will not charge

Common Problems That Trigger the P0AF9 Code

  • Auxiliary 12V battery failure
  • Battery Energy Control Module (BECM) failure
  • High voltage battery assembly failure

About the Author

Brad Kava is an automotive expert at RepairPal, the leading online source of auto repair resources and estimates. With many ASE Master certified mechanics on staff who have decades of experience, RepairPal knows all the fine points of car repair.

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