Question

P1133 CHEVROLET -installed 02 sensor above the catalytic converter, still getting code p1133??

Answer 1

P0420 Catalyst system low effeiciency

P1133 H02S insufficient switching Sensor 1

These 2 codes can be caused aby a MAF (mass air flow) being insufficient. The MAF provides the ECM with information to balance and deliver the correct fuel mass to the engine.A 2005 ecotech may have a cleanable MAF unit  where a MAF cleaning may restore it.

Comments

when i get the 1133 code the car tries to die and runs like its only running on 3 cylinders, i can cut the engine off for a few seconds and it will start and run just fine.

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You definitely have a lean misfire, check fuel pressure,  you need 50-60 psi (key on engine off)