Diagnostic article Generic OBD-II
P0A82: Battery cooling fan commanded on but speed feedback stays low
P0A82 compares the fan-on state with cooling-fan speed feedback in this GM BAS hybrid system.
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Documented application
2009 General Motors diagnostic parameter file 09OBDG08 Engine Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P0A82 is the battery cooling-fan stuck-off check in GM's BAS hybrid section. The controller expects fan-speed feedback when the fan state is on. The published failure condition is speed feedback below five percent during that commanded-on state.
Speed feedback is the decisive input here
The same page separates fan-speed feedback from fan-control feedback. P0A82 uses the speed feedback to judge whether the fan appears to remain off. The neighboring P0A84 control-circuit check uses a different feedback quantity. Mixing those two signals can lead to the wrong interpretation of a scan-tool display.
The monitor requires the energy-storage controller to be in Run or Service, with system voltage between its documented limits. It accumulates 188 failures in 250 samples at a 20-millisecond sampling rate. A brief quiet interval before the command qualifies does not automatically reproduce that pattern.
The code does not locate the failure
Low speed feedback under an on command can establish a functional disagreement without identifying whether the fan, its power/control path or feedback reporting is responsible. Use the vehicle-specific cooling-system diagnostic procedure to separate those possibilities.
Preserve the command and both available feedback types before clearing faults. Verification should show credible speed response during the required on state and completed monitoring. Hearing a fan run once or erasing P0A82 does not prove reliable battery-cooling operation.
Source and applicability
2009 General Motors diagnostic parameter file 09OBDG08 Engine Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established. This explanation describes the documented monitor, not a universal repair procedure.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Hybrid/EV Battery Pack Cooling Fan 1 Performance/Stuck Off
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT