So I have a 2016 lancer, it has about 65000 miles on it. I got it used and now it’s making a rattling sound as well as when my wife and I are driving it it will sometimes chug and blow some white or blue (can’t tell because of the tint) from the tail pipe. I took it to an auto shop which they couldn’t tell me what’s wrong. And the computer I have isn’t pulling any codes. Also the rattling sound is only when driving and it’s either under the car or from the engine bay. Please help
I would check the noise first, I broken catalyst will show all those symptoms, and to diagnose it if it sounds like it is coming from inside the cat; hit the outside hard with hammer. The dent will stop the rattling for awhile. I always check for blown head gasket,vacuum leaks, fuel trims. there is usually something that killed the cat, it might have been repaired already,might not be repaired and will kill your next too.