Oxygen Sensor Heater Signal

PURPOSE
To keep the oxygen sensors (G3/1 and G3/2) at a consistant operating temperature (approx. 600 °C / 1112 °F), the HFM-SFI control module controls the oxygen sensor heating element. (Either directly or through the relay module (K35) depending on model. Refer to wiring diagram.)

OPERATION
When the engine is started, the oxygen sensor heating element is in operation. If the engine exceeds 5500 RPM, the heating element is turned off. Operation restarts when the engine speed drops below 5000 RPM.