More details needed. What sensor? (ie. Oxygen, temperature)
Furthermore, the Check Engine Light causes the car's computer (ECU) to store a diagnostic code (OBDII code). This code can be retrieved by a mechanic with a scanning tool. The code is then decifered and used to help isolate the cause of the problem.
Here's a list of the codes - http://www.toyotanation.com/forum/showthread.php?threadid=31404
Furthermore, the Check Engine Light causes the car's computer (ECU) to store a diagnostic code (OBDII code). This code can be retrieved by a mechanic with a scanning tool. The code is then decifered and used to help isolate the cause of the problem.
Here's a list of the codes - http://www.toyotanation.com/forum/showthread.php?threadid=31404