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 "Control Circuit Inspection" procedure.

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

IG "ON".

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

Is the measured voltage within specification ?

	▶ Go to "Component Inspection" procedure.
	▶ Repair Short to power in control circuit and then, go to "Verification of Vehicle Repair" procedure.