This B1635 Code has multiple meanings and it is important to locate the problem of the engine following the code. It seems that the body engine has the main problem. You can solve the problem if you know the name of the manufacturer and model of the car. If you do not have experience and machineries, you should not try to solve the problem. There are 2 main types of cylinder deactivation system what are used now a day. The B1635 code is used for the pushrod design what uses solenoids to change the oil compression distributed to the lifters. Test drive is important for checking the car.