CEL after STILLEN G3 intakes, headers, exhaust and BERK HFC install

evrumohr

I recently had my STILLEN headers, exhaust and Berk HFC installed and have been getting a CEL light. I had the CEL scanned and I got the ff codes initially:
P0113 (Intake Air temperature Sensor 1 Circuit High)
P0031 (HO2S Heater Control Low Bank 1 Sensor 1)
P0051 (HO2S Heater Control Low Bank 2 Sensor 1).

The mechanic then reset it and we got these codes after:
P1148 (Closed Loop Fault Detected Bank 1)
P1168 (Closed Loop Fault Detected Bank 2)

I called Stillen and asked if they knew what it could be. I was told to try to disconnect the battery for 10 mins and see what happens. I did, and got the same thing. FYI, I remember that the mechanic did NOT disconnect the battery during the entire install. And my stock intake boxes were also disconnected because the install of my Stillen G3's could not be completed since I got the wrong parts.

So my questions are:
1. Do I need to replace any parts? (sensors, etc.)
2. Which parts are defective?
3. What do I need to do step-by-step to resolve this issue?

PLEASE HELP! I need to get this resolved soon since I dont have any other means to get to work! Any help will be VERY MUCH appreciated. TIA!