Oxygen Sensor Relay: Description and Operation

Oxygen Sensor Heating System:

The Heated Oxygen Sensor Control Module is energized via the Motronic control module. ON or OFF status of the relay depends on several conditions:

Relay ON conditions

^ If the intake air temperature is below 62°F (16°C), when starting the engine, the relay will be turned ON when the coolant temperature reaches 104°F (40°C).

This should allow enough time for any condensation that might be on the oxygen sensor to evaporate.

^ If the air temperature is above 62°F (16°C) when starting the engine, the relay is turned ON immediately.

Relay OFF conditions

^ The relay is turned OFF at high engine speed and load to prevent overheating of the oxygen sensors ceramic heating element.