02 heater wire

[Garageaholic]

What does that heater wire do? how necessary is it? (4 wire 02 sensor version)

[rs4pro3]

The sensor has to be at a certain tempature to work effectively, the heater wire heats the sensor up when you first start the car, so the ecu gets a better signle from the sensor, vesus waiting for the exhuast gases to heat it up.

[Garageaholic]

oooooh i see, so the heater wire is going TO the oxygen sensor,, not FROM the oxygen sensor...

[rs4pro3]

correct, it goes from the o2 heater relay to the sensor.