How to reset the computer in a 20003 jag s type

Disconnect your battery for 3 minutes. If it doesn't. You need a scanner.

Unfortunatly you have to flash the system at the dealership or buy an OBD2 to USB cable and Jag can bus software and do it yoursely, either way same price.

back it to a dealer as although iam not sure here but i think this is a similar problem to teh S type jag the computer brain is having seizures and the only solution here is a new computer

Air intake temp sensor. Check the wiring to the sensor and make sure there are no bad places or hard kinks. If that doesn't change things replace the sensor.

takes a special scanner to do that and usually you need to go to JAG and pay thier sorry azz $125 to do it sad but true

on a xj they are in the boxes by the light units ... X type iu dont know because i havent worked on one as yet?? as yet

Have you another key and fob ?

Try lock/unlock cycle with new key + fob. Your key may be corrupted.

Try also just unlocking the car with the key (not the fob) as soon as you unlock the door put the key in the ignition immediately and see if the car starts.

If you have your radio code it may be worth trying a total reset (leave the car unlocked) disconnect the battery and leave for 20 mins. then reconnect, most systems will then reboot and this MAY help?
Failing all the above it looks like dealer time - more ££ss

good luck !

check your menu and see if you can reset factory settings press 3 sec and reset

press mode until clock flashes then put 12hrs or 24hrs then type in the time then finish

$2000.00 computer at the Jag dealer will fix the problem.