P073D: commanded neutral does not match actual transmission range

P073D means the transmission did not achieve or retain Neutral as expected in the GM monitor reviewed here. The diagnostic compares the commanded range with the actual arbitrated transmission range. It is not presented as a gear-ratio calculation or a direct test of one clutch.

A valid range that disagrees

Monitoring requires the actual transmission-range information to have good status and the commanded range to be Neutral. When the actual arbitrated range is not Neutral, the failure timer increments. The code qualifies when that duration reaches the expected shift time; this table does not publish one fixed number of seconds for every application.

The good-status prerequisite matters. A valid but unexpected range value is different evidence from an unavailable or invalid range signal. The “achieve or remain” wording also means the fault need not be limited to the initial selection of Neutral.

When the check is active

The monitor is excluded during the code-clear function and manufacturing mode. Its enable description includes Run/Crank or accessory/wakeup operation and an internal active period that ends when Park is achieved and accessory/wakeup is off. Reporting is Type B over two trips.

When evaluating captured data, compare the commanded range, actual range and range-status validity over the selection interval. An immediate disagreement before the permitted shift time expires is not equivalent to the documented fault. Verification should demonstrate that actual Neutral is reached and retained under an enabled check. The source does not identify the failed mechanism or establish vehicle applicability beyond the 2025 GM monitor file.

Source: GM monitor, PDF page 644.