Component Inspection

■ Check HO2S 

1. Visually/physically inspect the following:
   • Ensure that the HO2S is securely installed.
   • Silicon contamination. This contamination will be indicated by a white powdery coating on the portion of the sensor exposed to the exhaust stream and this will result in a but false (high) voltage signal
   • Fuel, engine coolant or oil contamination
   • Use of improper sealant
   • If contamination is evident on the HO2S, Fix the source of the sensor contamination before replacing the sensor to prevent future contamination. Go to "VERIFICATION OF VEHICLE REPAIR " procedure.
2. Warm up the engine to normal operating temperature and let it idle.
3. Connect Scantool and monitor the O2 SNSR VOL.-B1/S1 parameter on the Scantool data list.

   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) at idle. (Refer to "SIGNAL WAVEFORM & DATA )

4. Is sensor switching properly?

   YES 

   • Check for poor connection between PCM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

   NO 

   • Check HO2S for contamination, deterioration, or damage. Substitute with a known-good HO2S and check for proper operation. If the problem is corrected, replace HO2S and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.