Thread: O2 sensor
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Old 04-15-2015, 04:24 AM   #2
Burg Boxster
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Join Date: Nov 2006
Location: In the garage...
Posts: 1,702
First - are you certain the sensor is bad? A CEL for a sensor ONLY means the value being returned by sensor is out of range. Period - end of story. Grab a multi-meter and test actual sensor and look for wire issues while there.

Next - sensors rarely if ever go bad simultaneously in pairs or series; unless there is a known upstream issue fouling them (this is different than them returning faults in pairs or series). So, again, before replacing, test the sensor(s) returning a value outside of norm (fault). If it tests bad, replace that sensor and only that sensor. They are not cheap $15 wear item parts like wipers. Further, don't monkey around w/ moving them. Just replace the one (or in the very unlikely event ones) which tests bad.

Finally - if sensors test OK, then they are ok and your issue is further upstream. For instance, one will get a CEL showing two or possibly all four (2 pre, 2 post cat) O2 sensors are bad. They (or an unqualified mechanic) will end up throwing $100+ each plus labor at sensors only to have CEL still active. Finally they will check and realize MAF is bad and now need to put some nice coin towards that too. Basically, double the repair bill than needed...

Good luck
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