H30 - HO2S Check

- Key "OFF".

- Heated Oxygen Sensor (HO2S) disconnected.

- Connect Digital Volt/Ohm Meter (DVOM) to HO2S circuit and HO2S GND or SIG RTN at the HO2S connector.

- DVOM on 20 volt scale.

- Create a vacuum leak to cause HO2S to go lean.

- Disconnect any vacuum hose from the manifold vacuum tree.

- Start engine and run at approximately 2000 rpm.

- Does the DVOM indicate less than 0.4 volt within 30 seconds?

Yes -- Go to H90. H90 - Check Continuous Monitor Diagnostic Test Mode

No -- Replace HO2S. Reconnect vacuum hoses. Drive vehicle 5 miles/55 mph. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)