Sad plea for help on O2 sensor

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Jun 1, 2009 | 04:24 AM

Mrider

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Sad plea for help on O2 sensor

Ok, this is sad. I have looked over the different posting on O2 sensors and can not ID the connectors in the engine bay.

I have a 2002 1.8t A4. I am getting a P0420 code and believe (would like) it to be caused by the O2 sensor (vs cat). I am trying to id which O2 sensor to replace and would like to use the multimeter trick to find out. Could someone help id the correct connector (color, etc) to check and which pins?

TIA

Jun 1, 2009 | 07:11 AM

Dublzero

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From: the head, MA

whats the deffinition of the code? since there are 2 O2 sensors, im not sure which one youre looking at.

Jun 1, 2009 | 07:56 AM

Mrider

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The code has something to do with not meeting eff for the bank 1 cat. From what I read, this can also be caused by an O2 failure. I am trying to determine which of the O2 sensors have failed by reading the resistance of the sensor with a multimeter at the end of the connector in the engine bay.

Thanks

Jun 1, 2009 | 08:54 AM

Dublzero

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From: the head, MA

most likely if its an o2 sensor it would be the rear one, seeing how the primary job for the rear O2 sensor is to monitor cat efficiency. you can just follow the wire and test the connector it leads you to.

have you had any misfires recently? or been running rich at all? if so, it could be your cat. over time, if fuel gets into the cat the material inside will crack and fall apart. you can simply bang on the cat lightly and listen for rattles inside.