P2120: APP1 disagrees across primary and secondary processor evaluations

P2120 has a general throttle/pedal sensor-D circuit label, but this GM row identifies accelerator-pedal sensor 1 as evaluated by a secondary processor. Its distinguishing condition is that the secondary reading is out of range while the primary processor still regards that sensor as in range.

Processor context changes the interpretation

The cited secondary APP1 limits are below 0.325 V or above 4.75 V. The row describes continuous or intermittent shorts or opens in that evaluated circuit. It also lists five-volt-reference fault exclusions and supply/reduced-power conditions that affect evaluation.

This is not simply the same event as a low APP1 report from both processors. The neighboring low- and high-signal diagnostics cover other combinations. Recording only one displayed pedal percentage can therefore miss the processor-level distinction the code was designed to identify.

Preserve the source's naming boundaries

The table's APP1 designation does not prove where a universally named sensor D is located on every vehicle. Use the actual vehicle's circuit mapping and controller data labels rather than translating the generic letter into a guessed connector or pedal component.

A technician should retain the exact fault, reference-supply state and available primary/secondary information. The source does not isolate a pedal, harness or controller defect, and its implementation counters are not presented here as a universal test duration. The appropriate electronic-throttle diagnostic procedure is needed to establish the cause and verify the relevant processor evaluation.

Source and applicability

GM 2009 09OBDG07 Engine Diagnostics, cited secondary-processor APP1 range monitor only. Individual vehicle, engine, wiring and calibration applicability has not been established from this parameter file.

General Motors source, physical page 107