P264F: An engine serial-number field left unprogrammed

P264F appears in the source as an engine serial number not programmed or incompatible fault. The documented check asks whether the engine serial number was correctly written. Its failure criterion is that at least one programmed serial-number digit contains the value 0xFF.

A stored-data check

The monitor runs continuously with a 250-millisecond test interval and requires the OBD manufacturer enable counter to equal zero. It lists a one-trip response. These details concern a controller's validation of stored identification data; they do not describe a combustion, sensor-voltage or mechanical wear threshold.

The hexadecimal value 0xFF is a data condition in the programmed field. It is not an engine code to stamp onto a component or a replacement serial number to enter. The source does not instruct the user to choose a value or copy identification from another vehicle.

What should be verified

Retain the controller identification, programming history and diagnostic record, then obtain the application procedure for checking the engine identification field. Recent controller or engine service is relevant history to investigate, but the table does not establish that such work occurred or that the installed engine is incompatible.

Any correction must use the vehicle's legitimate identification and authorized programming process. Verification should confirm that the required data is valid and that the monitor completes with its enable condition satisfied. Clearing the code without correcting an unprogrammed field can leave the same validation failure ready to recur. This summary does not certify the vehicle's identity or prescribe a universal programming sequence.

Source and applicability

2025 GM 06B documented monitor only; module and calibration applicability must be matched to the vehicle. GM PDF, page 497.