2006 Scion XA. Could not unlock doors with key fob. Used key to unlock doors. Alarm went off & would not go off. Had to shut the doors & lock with key. Now when I unlock the door with the key the alarm does not go off, but now the car will not start

SOURCE: How do I reset the check engine light for a 2006 scion tc?

YOU CAN GO TO ANY ADVANDED AUTO PARTS AND THEY CAN HOOK UP A OBD2 SCANNER, WE THEY DO ASK THEM TO RESET THE LIGHT FOR YOU.. THIS IS A FREE SERVICE TO THE PUBLIC..GOOD LUCK KEITH..

SOURCE: alarm for audi A4

Try disarming the car from the trunk. Sounds like the door lock switch is not deactivating the alarm, which it should, with or without the remote.

SOURCE: power door locks, scion xb 2005, drivers side.

replace the remote key battery.

SOURCE: need to change spark plugs in my 2006 scion xa

try this article. Its pretty simple.

http://scionlife.com/forums/showthread.php?t=16364

SOURCE: how to fix remote car key

1.Insert key in ignition and pull out
2. Within 5 seconds, insert the key in the ignition and pull out again.
3. Within 40 seconds, close and open the driver's door twice, then insert and remove the key from the ignition again.
4. Within 40 more seconds, close and open the driver's door twice, then insert the key in the ignition and close the driver's door.
5. Turn ignition switch from LOCK to ON to OFF three times, leaving the key on for one second and off for one second each time.
6. Remove the key from the ignition lock.

The doors will lock and unlock themselves at about 2 second intervals. The number of times that the doors lock is the number of remotes that are programmed into the car. If the car locks/unlocks 5 times, there are no codes registered.