1. Check Rear HO2S

1. Check the rear HO2S for the following items:
   • HO2S damage
   • Open or short in HO2S circuit
   • Refer to  DTC P0136: O2 SENSOR CIRCUIT OPEN CHECK (BANK 1, SENSOR 2) , DTC P0137: O2 SENSOR CIRCUIT LOW INPUT (BANK 1, SENSOR 2)  and/or DTC P0138: O2 SENSOR CIRCUIT HIGH INPUT (BANK 1, SENSOR 2)   for a detailed inspection procedure. 

Is the rear HO2S okay? 

Yes: Go to next step.

No: Replace it.