: You need to find the in service date for this car. Ask your dealer and they can look it up for you. BMW warranted the engines for 6 yrs or 100k. Since this is a 94 the six years are up this year. Personally I would say buy the cat anyway. If you have been a previous BMW owner and established a relationship with your dealer I think BMW will stand behind the car. Even if you have to pay part of the engine replacement you will still have a good deal. The complete cost of engine replacement is approx. 5-7k depending on dealer and other work. A 94 840 in good shape should be worth anywhere from 28-32k. : I just bought a 94 840 with 33k and had the engine checked on May 19th (warranty expired on May 20th) and BMW replaced the engine.