Diagnostic article Generic OBD-II
P0A87: Power-module current plausibility is tested in current-limit mode
P0A87 compares the power-module current reading with its expected current-limit operating state.
Read before applying this article
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.
P0A87 is a performance check of the auxiliary power-module current sensor in GM's BAS hybrid summary. The source evaluates the measured current against the stated high-current reference while the module is in current-limit mode. It is not a general check of every current reading during ordinary operation.
The operating mode creates the reference
The published comparison uses the difference from a 130-amp reference, with a 39-amp deviation threshold. The module output voltage must exceed seven volts and the higher-voltage output must exceed 28 volts. The evaluation lasts 25 milliseconds in the documented current-limit state.
Those conditions explain why an ordinary low-load current reading cannot be judged against this monitor's reference. The figures are calibration data, not a request to load a hybrid power module to its current limit for testing.
Performance differs from an electrical extreme
The adjacent P0A88 and P0A89 entries check low and high sensor voltages directly. P0A87 instead asks whether a potentially in-range signal makes sense for the known operating state.
Preserve the module mode, voltage information and measured current from the failure record. Use the exact hybrid service procedure to distinguish sensor credibility from power-module behavior. Verification should include completed qualified monitoring; clearing the code or seeing a plausible current at a different load does not establish that the current-limit comparison now passes.
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
14 Volt Power Module Current Sensor A Circuit Range/Performance
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