Who guarantees the hidden defects of a car after sale?

The questions are :

1. Who did you buy the car from?

2. Is there a warranty on the car?

3. What is the type of contract you have signed when you bought the car?

The bank has nothing to do with it and will not stop the EMIs since the bank has only financed the car and the liability remains fully yours till you close the loan and/or transfer the car to someone else.

Your issue needs to be sorted out with the seller of the car, not the bank.