So, BMW Long Beach has for three weeks blindly replaced parts trying to figure out my SES code and why my car won't pass smog test this time. I've thrown in the hat with this and told them to reassemble what they've taken apart and get the car running since we're leaving on Christmas vacation next week. My question...They want to replace both MAFS for $1300. I think those are a simple replacement part, a few clamps and you're done, or is there some clever engine mapping or something else that needs to happen after installing new MAFS?