I just changed the battery in the fob I use all the time. It locks and unlocks the car, panic alarm works etc, however, when I go to start the car it just turns over and wont start.

The engine warning light comes up orange instead of red and stays on until I turn the ignition off.

If I change it to the second key fob key I have the car starts fine.

I have tried several suggested procedures including: lock/unlock 5 times, lock/unlock 3 times, set panic alarm on/off, another new battery and it still wont start the car. everything else in the car electrical seems to work fine.

I have searched the web for days looking for a solution and nothing so far works. Why would this occur?

Further, If what I have read is correct, (have read hundreds of articles) the key is coded to my car, therefore a battery change shouldn't affect the starting of the car.

Anyone got ideas as to how I can fix this? I am very worried about changing the battery in the one that works, and worst still that should it go flat while away from home i will be stranded somewhere.

Thanks.