Disconnect the HO2S(s) and PCM/ECM connectors and inspect for looseness, poor connection, bending, corrosion, contamination, deterioration or damage. Reconnect the connectors.
Connect the GDS and go to “Current Data”.
Monitor HO2S(s) values in Current Data, check and wiggle the harness(es), connector(s), and terminal(s).
Any change in the values indicates a poor connection. Was a connector problem found?
![]() | ▶ Repair the connector. Go to "Verification of Vehicle Repair" procedure. |
![]() | ▶ Go to "Control Circuit Inspection" procedure. |
IG "OFF".
Disconnect HO2S connector.
IG "ON".
Measure voltage between VN terminal of the sensor harness connector and chassis ground.
Specification : Approx. 2~3V
Measure resistance between VN terminal and other terminals of the HO2S harness connector.
Specification : Infinite
Is HO2S display near the specification?
![]() | ▶ Go to next step as below |
![]() | ▶ Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure |
HO2S must have a clean air reference to function properly. The air is obtained by way of the sensor wire(s). Do not attempt to repair the wire(s), connector, or the terminals.