Just bought a 2000 prelude, been sitting on the drive way for 6 months before i bout it?

when i first got the car i knew i should burn the gas it had sitting in the tank, so i drove it around for about an hour and it finall got to E. everything seemed great, then the next day the engine light came on, and the gears are getting a little harder to push in, so my question is, should i drain all the fluids inside the car and refill them, and also, if everything drives fine what are some good reasons why the check engine light would be on? your answers will be appreciated thaaank you!