DTC P0133: HEATED OXYGEN SENSOR NO. 1 CIRCUIT - SLOW RESPONSE Chevrolet Venture I

Note. For circuit reference, see WIRING DIAGRAMS article.

Circuit Description

PCM continuously monitors Heated Oxygen Sensor (HO2S) activity for 100 seconds. During this period, PCM counts the number of times that a rich-to-lean and lean-to-rich response is indicated and adds the amount of time taken to complete all transitions. With this information, an average time for each transition can be determined. If average response time is too slow, DTC will be set. A lean-to-rich transition is indicated when HO2S voltage changes from less than 300 mV to greater than 600 mV. A rich-to-lean transition is indicated when HO2S voltage changes from greater than 600 mV to less than 300 mV. An HO2S that responds too slowly is likely to be faulty and should be replaced.

For duplication of DTC, ensure

1. No active TP, MAP, MAF, IAT, ECT or AIR, misfire, fuel injector circuit, EVAP system and fuel trim DTCs are set.
2. Engine has been running in closed loop fuel mode for at least one minute.
3. Engine speed is 1000-3000 RPM.
4. MAF between 10-30 grams per second.
5. System voltage 9-18 volts.
6. Engine speed 1000-3000 RPM.