A4 Sedan V6-2.8L (AFC) (1996)
Heated Oxygen Sensor - G39/G108
Heated Oxygen Sensor - G130/G131
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The oxygen sensor's response characteristics depend upon temperature. By heating the oxygen sensor it is possible to achieve effective closed-loop
control of emissions at low engine and exhaust-gas temperatures.
DIAGNOSIS OF THE OXYGEN SENSOR'S HEATER:
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The system uses measurements of electrical resistance in the sensor's heater to verify that it is operating correctly.
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Condensation, the formation of which is a particular hazard in the cold-start phase, can cause damage to the heated oxygen sensor under
unfavorable circumstances. Therefore the heating of the before-catalyst sensor is conducted directly after engine start, while the pre-catalyst sensor
is heated after exceeding a calculated catalyst temperature.