Was working on a 2012 Civic in my home shop three days ago and the check engine light kept coming back after clearing codes

I swapped the O2 sensor, checked the wiring, and was about to order a new cat. Then I saw a tiny crack in the exhaust manifold gasket, right before the upstream sensor. Fixed that cheap gasket and the light stayed off. How often do you guys find the real problem is something simple you almost missed?

3 comments

3 Comments

faith_schmidt1mo ago

It's always the cheap, simple stuff that gets you. I've wasted so much time and money chasing ghosts, only to find a loose ground or a split vacuum line.

emma6841mo ago

Oh man, @faith_schmidt, you are so right! I spent a whole weekend once trying to figure out why my car was running rough. I was ready to replace the fuel pump! Turns out it was just a cracked rubber hose going to the air filter box, a five dollar part. Felt like such a fool after all that stress. It's crazy how the smallest, cheapest thing can cause the biggest headache.

grace5651mo ago

Right? I used to swear it was always the expensive sensors or something major, but a $15 gasket and 20 minutes fixed a three-day headache for me too. Totally changed how I approach a check engine light now.