Circuit Description

PCM monitors Heated Oxygen Sensor (HO2S) activity for 100 seconds. PCM determines if HO2S 1 is functioning properly by counting number of HO2S 1 Lean/Rich (L/R) and Rich/Lean (R/L) switches. If PCM determines that HO2S 1 did not switch enough times, DTC 1133 is set.

Conditions required to set DTC are:

• No fuel trim, injector or HO2S 1 heater circuit DTCs set.
• No ECT, IAT, MAF, MAP, or TP sensor DTCs set.
• No EGR or EVAP DTCs set.
• Engine operating in closed loop mode.
• Conditions present during 100 second monitoring period.
• TP angle value 10-20 percent.
• L/R and R/L switches less than 50 on VIN 1.
• L/R and R/L switches less than 40 on VIN K.