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Home >> Subaru >> 1990 >> Legacy Sedan 2WD F4-2.2L SOHC >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Oxygen Sensor >> Description and Operation >> O2 Heater
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O2 Heater

PURPOSE
To heat the O2 sensor.

LOCATION
An integral part of the O2 sensor.

OPERATION
The O2 sensor does not operate until a certain temperature is reached. The heater warms the sensor up faster than if it had to rely simply on exhaust gas heat. The MPFI system then controls the A/F mixture sooner, reducing exhaust emissions.