Circuit Description
WARNING: This page is about a different variant/trim than selected.
VCM supplies a voltage of about .45 volt between HO2S signal and HO2S ground circuits. HO2S varies voltage from about one volt with rich exhaust to .1 volt with lean exhaust. HO2S produces no voltage and acts as an open circuit when temperature is less than 600°F (316°C). An open sensor circuit or a cold sensor causes open loop operation.
HO2S heater provides for faster sensor warm-up allowing sensor to become active in a shorter period of time and remain active during long extended idle. DTC determines if HO2S heater is operating properly by monitoring amount of time necessary for HO2S to become active after start-up.
DTC will set when the following conditions are present:
- System voltage greater than 9 volts but less than 17 volts.
- MAF is less than 27 gm/s.
- Engine run time greater than 2 seconds.
- ECT and IAT less than 90°F (32°C).
- Difference between ECT and IAT is less than 41°F (5°C).
- Elapsed time to obtain .3-.6 volt is greater than calculated value.
- Excessive amount of time for HO2S to become active after start-up.