P082A: X-axis sensor 1 can fail path or correlation checks

P082A monitors the gear lever's X-position sensor 1 in the reviewed GM strategy. The table names its measured quantity Alpha 1. Two different findings can set the performance code: a position outside the permitted shifter movement path, or a percentage disagreement that reaches the calibrated Alpha limit.

The disagreement limit is not constant

The supporting table expresses Alpha disagreement in percent and varies the permitted difference with two position coordinates. Its values span 7% to 20%. A blanket rule that any fixed percentage difference is acceptable everywhere would therefore misrepresent this monitor.

The path check and the disagreement check also answer different questions. A reading can be implausible for the physical movement path even before a comparison exceeds its limit. Conversely, an individually plausible position can participate in excessive disagreement.

Evidence for verification

Calibration enablement is required. Failure qualification uses 10 out of 12 samples, and the reporting class is Type B across two trips. The summary does not provide a sampling interval, so it does not establish a fixed elapsed set time.

A useful evaluation follows Alpha 1 across the affected lever movement and relates any disagreement to the applicable coordinates in the supporting map. Checking only one stationary position can miss a path-dependent failure. The source does not specify a sensor voltage, connector pin or replacement assembly. These facts apply to the 2025 GM monitor and supporting table; the actual shifter and calibration must be identified before using them diagnostically.

Source: GM monitor, PDF page 655; GM monitor, PDF page 1635.