Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary and go to "Verification of vehicle Repair" procedure.
	▶ Go to next step as below.

IG "OFF" & Disconnect HO2S(S1) connector.

IG "ON" & ENG "OFF".

Measure voltage between power terminal of HO2S(S1) heater harness connector and chassis ground.

Is the measured voltage within specification?

	▶ Go to "Control Circuit Inspection" procedure.
	▶ Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.

IG "OFF" & Disconnect HO2S(S1) connector.

IG "ON" & ENG "OFF".

Measure voltage between control terminal of HO2S(S1) heater harness connector and chassis ground.

Is the measured voltage within specification?

	▶ Go to "Component Inspection" procedure.
	▶ Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.