Good Evening, to anyone that reads this. Recently I got a code for P0420 and a C1109. I'm particularly worried about the P0420 as changing the cats are expensive. Which I'm going to have to do if I wanna pass emissions. But I've read online that cats going out with that error code resulted from something else going bad. And I couldn't think of much to cause it to go bad other than, prior 3 months I changed my spark plugs. Idk if that is the issue cause if I never got a check engine light for it (unless it doesn't occur for faulty sparkplugs) however I did get a check light for MAS sensor after changing sparkplugs but that disappeared after cleaning it. I'm scared that I change my cats now and not fix the problem that caused my bad cats, the new cats i put on would go bad in few months. Also I have no clue what the C1109 code is I searched it and I keep getting results for transmission out put speed sensor which sounds very serious or results for ABS. I am not that handy or knowledgeable on car mechanics by any means. I just do maintenance that I think are relatively easy with a lot of prep and utube videos. Thank you for reading my rant.

 

I would start by checking the abs fuse and the battery. Looks like this code can cause others.

 

TY I'll start with that.