Anti-theft Immobilizer: Security system that prevents the car from starting if the ignition key is not the correct one.
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The anti-theft or immobilizing system is automatic and it begins working as soon as the key is inserted. If the key is not the right one, this system activates different blockages in the car to prevent it from starting. It blocks the injection system and that disables the entire ignition system of the car.
Also to reset the anti theft. Shut all doors. Take key out in lock turn as to un lock but don't leave key for 40 to 60sec. Than do the same turning to lock poss. Get in and start. It worked for my 2003