Oxygen Sensor Relay: Testing and Inspection

A/F Sensor Heater Relay




1. REMOVE RELAY BOX COVER
2. REMOVE A/F SENSOR HEATER RELAY (Marking: A/F HTR)




3. INSPECT A/F SENSOR HEATER RELAY CONTINUITY
a. Using an ohmmeter, check that there is continuity between terminals 1 and 2.
If there is no continuity, replace the relay.
b. Check that there is no continuity between terminals 3 and 5.
If there is continuity, replace the relay.




4. INSPECT A/F SENSOR HEATER RELAY OPERATION
a. Apply battery voltage across terminals 1 and 2
b. Using an ohmmeter, check that there is continuity between terminals 3 and 5.
If there is no continuity, replace the relay.

5. REINSTALL A/F SENSOR HEATER RELAY
6. REINSTALL RELAY BOX COVER