If you need oil or filters or throttle body cleaner, etc..., run by Autozone and let them read your OBD2 code for you, why guess. It's usually free, but I try to make it worth their while so they keep it that way. There's always something I'll need down the line, so it also saves me a trip later.
Recently I had a slow O2 sensor code (P0133), but before I could clear it, it reset itself. That was a month ago and it hasn't returned yet.
Get the code and post it, lots of peeps have the service manuals and there are some pros here also.
2009 Hyundai Elantra Touring (I30cw)
@10 miles when it left the lot...@21K+ now.
'01 2.3L LX Sedan @217K+ miles... Original owner,
handed off to my son.
Had 6th Genititus, on 2nd trans @112K