The trouble B1694 Code has a definition and if you do not get the correct meaning of the code, you cannot solve the problem. The meaning of the code changes vehicle to vehicle. The OBD 2 B1694 code and tailpipe difficult are 2 dissimilar methods to recognize cars in need of mending. The OBD system looks for fragmented or faulty emissions control mechanisms while tailpipe tests sample a vehicle’s finish to see if it is above or under certain set limits. When you find the car problem is solved by the engine, you should take car for test drive and if everything is ok, then take the car.