On a 2019 Lexus GX460, the message“A program cannot be read. Please consult to a dealer.” usually indicates a problem with the navigation/infotainment head unit software, not an engine or transmission issue. Common causes include a failed navigation SD card, corrupted software, low voltage/battery issues, or a faulty multimedia unit. [thetoolstrunk.com], [clublexus.com] Did the problem start after a battery replacement, jump start, or dead battery? Is the screen stuck on the error, or does it reboot repeatedly? Are radio, navigation, backup camera, and climate display functions affected? Quick checks: Verify battery voltage and charging system operation. Perform a hard reset by disconnecting the negative battery terminal for 15-30 minutes, then reconnect and power the vehicle to ACC mode before starting. This has resolved the issue in some Lexus cases. [clublexus.com], [reddit.com] Check for a navigation SD card (if equipped) and ensure it is fully seated and undamaged. Inspect related fuses for the multimedia/navigation system. Most likely repair if reset does not work: Reprogram/update the multimedia unit. Replace a failed navigation SD card or navigation memory device. Replace the head unit if internal memory or hardware has failed. Forum reports show some vehicles ultimately required head unit repair or replacement. [reddit.com], [clublexus.com] Diagnostic conclusion: This is primarily an infotainment/navigation system fault, not a drivability concern. Start by checking battery history and performing a reset. If the message remains, scan the multimedia system with Toyota/Lexus diagnostic software (Techstream) and inspect the navigation storage device before condemning the head unit. [thetoolstrunk.com], [clublexus.com]