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 for setting DTC:

• No CKP, ECT, EGR pintle position, IAT, MAF, MAP, or TP sensor DTCs set.
• No fuel trim, injector or HO2S 1 heater circuit DTCs set.
• No EVAP system DTCs set.
• Conditions present during 100 second monitoring period.
• HO2S 1 L/R and R/L switches less than 45.