91 Geo tracker Check engine light go off no codes are flashing could it be the computer?

It is highly uncommon for the check engine light to go off and no codes to flash afterward. Check the wiring, especially where it connects to the computer. Ensure that the connections are secure and there is no corrosion. Look for any loose wires or connectors that may have come undone over time. Also, inspect the computer itself for any signs of damage or wear. If anything seems out of the ordinary, it would be best to take it to a professional for further diagnosis.