[piggy2017]

I bought a 325ci last Fri. The year is 2002 and has 76xxx miles on it.
This morning, the engine light is on, I read out the code is P1633.
it is Throttle Valve Adaptation; Limp Home Position .

Can Any one help me and tell me what does this mean? Is it expensive to repair it by dealer? or Can I do it myself? and how to do it by myself?

thanks in advance!