What are a consumers rights if purchasing a vehicle from a dealer and within the first 30 days the engine and catylltic coverters need replacing?

Is the vehicle purchased a new car or a used car? If a new car, the vehicle should be under the manufacturer's warranty. If a used car, possibly the existing warranty may not have run its course or an extended warranty was purchased when you bought the car.

It is somewhat hard for me to answer your question in that I need more facts concerning the vehicle's purchase and its age. In any event, you should take the car back to the dealer and see what can be done to get it fixed at the dealer's cost, not yours.