I have a 1997 S90. I replaced the MAF and the associated CEL code was eliminated along with the rough idle. The Check Engine Light was cleared, but has now reappeared with the code PO505. I have been driving it with no issues whatsoever, nothing seems indicate a problem. I would like to get this last issue resolved before it gets too cold to work on it outside. Your tips and help are appreciated.

 

Probably an air leak, probably around the maf/throttle body since you were just in there.