Visually/physically inspect following items
Inspect the front HO2S for any silicon contamination. This contamination will be indicated by a white powdery coating and this will result in a but false voltage signal
If contamination is evident on the HO2S, replace contaminated sensor and go to next step.
Warm up the engine to normal operating temperature and check that HO2S signal is active.
Install Scantool and monitor the "FR OXYGEN SNSR-B1" parameter on the Scantool data list.
Test Condition : Ignition "ON" & Engine "ON"
Specification : Verify signal is switching from rich(above 0.45V) to lean(below 0.45V) a minimum of 3 times in 10 seconds (voltage will vary between 0.1 and 0.9V).
Is sensor switching properly?
YES
Thoroughly check connectors for loose or poor connections, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
NO
Go to "W/Harness Inspection" procedure
