It's not actually a switch--it's referencing the Heated O2 sensor's process of switch-ing, the "11" telling you it's Bank 1 (driver's side) and before the cat.
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean Trouble code P1132 means: Lack Of HO2S11 Switches - Sensor Indicates Rich
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean
p1131 = lack of HO2S11 switches - sensor indicates lean
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean
Trouble code P1131 means: Lack Of HO2S11 Switches - Sensor Indicates Lean