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Old 08-16-2003, 04:31 AM
Posts: n/a
I thought it only was needed for the first 5 minutes when the car is started??
The O2 sensor warms up after about 5 minutes and starts sending voltage signal to the ECU thereafter for as long as the car is running.

It senses the oxygen level in the exhaust and signals the ECU to lean/richen the mixture when necessary.

If you use a voltmeter to check pin 3 of your X11 connector, you will see that on startup, the duty cycle is 50% which indicates that the O2 sensor is not working (coz it hasn't warmed up).

Once the sensor has warmed up, you should see a fluctuating duty cycle on pin 3 which can be anywhere between 0 to 100% depending on your current mixture.

Fluctuation at less then 50% (say between 35% to 45%) is rich and fluctuation at more than 50% is lean.

My 2 cents.

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