P1133 CHEVROLET - HO2S Insufficient Switching Bank 1 Sensor 1
- Vacuum leak
- Faulty Heated Oxygen Sensor (HO2S) Bank 1 Sensor 1 harness is open or shorted
- Faulty Heated Oxygen Sensor (HO2S) Bank 1 Sensor 1 circuit poor electrical connection
The Powertrain Control Module (PCM) monitors the Heated Oxygen Sensor (HO2S) activity for 90 seconds after closed loop operation has begun. The PCM determines if the front HO2S is functioning properly by counting the number of HO2S-1 Lean/Rich (L/R) and Rich/Lean (R/L) switches.