Oxygen Sensor (O2S 1)

A scan tool has several parameters that indicate the state of the exhaust gases: O2S 1 voltage, Short Term (S. T.) fuel trim, and Long Term (L. T.) fuel trim. A problem in the O2S 1 circuit should set a DTC P0134 (open circuit), DTC P0131 (lean exhaust indication), or DTC P0132 (rich exhaust indication). A faulty or lazy sensor will set a DTC P0133 (slow response) or a DTC P1133 (insufficient switching).