DTC Help

P1131 Lack Of HO2S11 Switch - Sensor Indicates Lean
1151 Lack Of HO2S21 Switch - Sensor Indicates Lean

Appears your running lean.
I've seen header/manifold leaks cause a lean code, also I've heard sometimes when you go to LT's you get a lean code.
Also kinda odd but my buddies cobra threw lean codes when the o2 sensor's went out.