Monitor Scantool Data

Warm up the engine to normal operating temperature and check that HO2S signal is active.
Connect Scantool and monitor the "HO2S (B1/S1)" parameter on the Scantool data list.
1. 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).
  
  Fig 1: Display HO2S Heater Data (Normal Idle Status)
  
  Fig 2: Display HO2S (B1S1) Data (Signal Circuit Open)
  
  Fig 3: Display HO2S (B1S1) Data At Lean
Is sensor switching properly?
YES
1. Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for loose or poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure
NO
1. Go to "W/HARNESS INSPECTION " procedure