AllanJJ

First, here's what I've done on my car recently that's in some relation to these codes,

• Intake Manifold Gasket Replacement
• Fuel Filter Replacement
• Vaccum Lines
• Both Upstream O2 Sensors

These two codes, P0171 and P0174, I received off of a new device I'm trying out. It's a T-Mobile SyncUP Drive. It popped up in the app about 2 days after driving around with the unit installed.

However, the check engine light has not been on since doing any of the tasks above. So I've also tried scanning the codes using my OBDEleven, not a single thing comes up.

So so my guess as to where these codes might possibly be from is my vacuum lines, when reinstalling the intake and the new vacuum lines, I was having some issues with following the diagram under the hood, I looked up pictures and looked on forums, and got them back to what I believe was the correct way.

What would be the best thing for me to check as to why these codes came up?