So my engine blew up, and I've been looking for a new good used one and the only parts car i could find has a B5244S3 in it, even though it is the same year and model Volvo S40 2.4i 2007, if i buy this engine would it be plug and play mine has the B5244S4 in it? or should i also buy the ECU of this engine?
Thanks for the answers

 

where are you located? Oddly the Volvo modular engine wiki page skips over the S3 version. The S4 version should be readily available as it was used in the S40/V50/C30/C70 models from 2004 to 2010. If you are in the US, try using car-part.com to see what yards have one. Also when you say your engine blew up, do you know if you need a top end, bottom end or both?