I just had my transmission rebuilt on my 2005 Acura TSX ..I got the car back & the car drove fine for 4 days then all of a sudden it would not restart. The fuel appears to be pumping but I was told it could be the main relay or immobilizer that could of went bad. any suggestions anyone? or has anyone has similar situations?

 

Are you using the same key? Maybe the keys got de-programmed during the maintenance and they had to reprogram your key. If you are using an old key it may not be recognized by the immobilzer.

Other than that I have no idea.