o2 sensor troubleshooting

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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=128578
Printed Date: May 04, 2024 at 12:30 PM

Topic: o2 sensor troubleshooting

Posted By: mikeavery
Subject: o2 sensor troubleshooting
Date Posted: September 19, 2011 at 8:43 PM

I have a 1998 vw jetta that has o2 sensor problems. I've already replaced the o2 that came up from the obd II system and still having problems. Just wondering if anyone knows what the wire layout should be for the car side of the o2 sensor connector. I assume its 12v and 5v with a ground but i have a 4 pin connector so whats the 4th one for? heater maybe, thanks in advance

Replies:

Posted By: howie ll
Date Posted: September 20, 2011 at 4:28 PM

98 was a changeover year so I will give you two colours:-
WHITE/ red = 12V+ ign.
Brown to 0v (ground),
Black to engine management.Pin 38 0v
White to ditto, pin 15, 0.1 to 1v+ fluctuating, with a hot engine.

Blue / YELLOW =12V+ ign.
Brown to BROWN / black (or vice versa) to 0v (ground),
Brown to engine management. Pin 25 0v,
Black to ditto, pin 26 0.1 to 0.9 volts, as above.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: oldspark
Date Posted: September 20, 2011 at 8:33 PM

And NEVER measure the sensor pin with a DMM except when in circuit. (IE - never measure sensor resistance with an Ohm-meter unless specially designed to do so.)