Code Definition

P0A99 — Hybrid battery pack cooling fan 2 circuit low

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0A99

P0A99 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0A99 is stored, the module has detected a signal or supply voltage lower than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0A99 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

This DTC is triggered when the hybrid/EV control module detects that the voltage on the Hybrid Battery Cooling Fan 2 control circuit is below a calibrated threshold while the circuit is expected to be in an active or standby state. This typically indicates a short to ground, an open circuit, or insufficient voltage supply to the fan motor or control input.

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