Cats are showing higher temperatures at the inlet than at the outlet. Bad cats?

[CO4x499]

Like the title says. I swapped my battery and it started throwing these codes:

P0171 -System too Lean (A/F Lean, Bank 1)

Secondary DTCs-

P0101 - Mass or Volume Air Flow Circuit Range/Performance

P0138 - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

I replaced the MAF, PCV, cleaned the intake throttle body. The mechanic said I need to replace my front/back O2 sensors and that my cats were fine. I live in CO so I need them to pass emissions (year away).

 

[xtremewlr]

Like the title says. I swapped my battery and it started throwing these codes:

P0171 -System too Lean (A/F Lean, Bank 1)

Secondary DTCs-

P0101 - Mass or Volume Air Flow Circuit Range/Performance

P0138 - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

I replaced the MAF, PCV, cleaned the intake throttle body. The mechanic said I need to replace my front/back O2 sensors and that my cats were fine. I live in CO so I need them to pass emissions (year away).

Listen to your mechanic and replace the O2 sensors before assuming it's the cats.

 

[gaber6]

A slight leak on the exhaust gasket may also throw an emission code. I bought all new stuff as it was old but once I had the right manifold on, I realized how bad the donuts were and only replaced the left donut and all was fixed. Now I have a spare oem and spare new replacement set of manifolds with the cats