Oxygen Sensor (O2S 1)

A scan tool has several parameters that indicate the state of the exhaust gases: O2S 1 voltage, short term fuel trim, and long term fuel trim. A problem in the O2S 1 circuit should set a DTC P0134, open circuit, or DTC P0131, lean exhaust indication, or DTC P0132, rich exhaust indication. A malfunctioning or lazy sensor will set a DTC P0133, slow response, or a DTC P1133, insufficient switching.