When I originally ordered my Mahle engine air filters from Rock Auto, it was only when I was ready to install them that I found out they were mismatched. The paper filament ion one was yellow while the other was white, and the date of production was on one, which was years old. Even the pleated paper looked different. I ended up biting the bullet and purchasing two from Jaguar, which ended up being a way better constructed filter with a wire mesh covering one side (rather than a bead of glue) keeping the paper elements together. I did not want to have any issues with the CEL going off because of any MAF issues. The filters that came out had 20,000 miles on them and were the OEM (identical to the ones I purchased) and said Jaguar on them. They looked pretty much like new, with very little to no discoloration or dirt. I guess I won't be replacing the air filters again (in my lifetime)...

 

I fitted BMC filters a year ago, expensive but look good quality
No issues with EML lights. I done a huge underbody cleaning job last year and cleaned the MAFs too, like everything it's a pig of a job on a Jag XK - the air boxes are impossible tight hence the mallet