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Old 04-15-2015, 03:28 AM   #1
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O2 sensor

I experienced a CEL for after cat sensor heater circuit . The tech at a local shop suggested to purchase 2 sensors, replace the before cat sensors with new ones and transfer the ones removed to the after cat position. Pelican parts shows different part numbers for the before and after applications. Are the connectors different, I am not interested in getting involved with soldering connections.

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Old 04-15-2015, 04:24 AM   #2
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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...

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Old 04-15-2015, 04:41 AM   #3
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Thanks for the help. The code was for the heater circuit , i am not sure how to test that with a multimeter assuming I can borrow one.
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Old 04-15-2015, 05:42 AM   #4
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Since O2 sensors don't go bad often its more cost and time effective to take the sensor from the other good side and swap sides to see if the code comes back on the other bank.

If the code does repeat but on the other bank then the O2 sensor replacement is warranted otherwise its most likely to be something else, like a wiring or dirty connector issue.

The before and after cat O2 sensors are definitely different so don't make substitutions if you want your codes to be resolved.

Testing the heater circuit for continuity may work if you know the sensor connector pinout details.

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