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O2 sensor


joeb

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ordered downstream sensor from rockauto. no pics at website. it has wrong 4 pin connector. they will credit my account and said keep it. can order another sensor/different brand. does anyone know if upstream/downstream sensors are identical except for plug? could i splice my old plug with new sensor wires? they are both 4 lead wires.

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I have done it beefore, just be sure to confirm that the sensor itself is the same, once you do that all you need to do is confirm wire colors and splice them together with heatshrink tubing to ensure no weather intrusion

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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ordered another sensor for downstream. turns out the part number is the same for an upstream sensor on a grand prix. which i also own. and as luck would have it, i get an occasional code for the downstream sensor on the grand prix. i could take a look under the hood and see what the grand prix sensor looks like but my kid has it at school.

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I had the same problem on a 3100 Chevy, wrong connector, my fault for no looking at the connector in advance.. Rockauto took it back in my case and I bought it locally

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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got 2nd sensor. still has wrong plug. sensor 1 was #273. sensor 2 was #272. #273 is supposed to be discontinued. tech at website said order a different brand next time. going to send back sensor #2.

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got 2nd sensor. still has wrong plug. sensor 1 was #273. sensor 2 was #272. #273 is supposed to be discontinued. tech at website said order a different brand next time. going to send back sensor #2.

Believe it or not, its the way they describe it, I kept saying rear bank, and its called a pre-cat in my case, its not the rear bank, go figure, look into that idea...

Mine is a V6 3400 Chevy

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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gm manual. do not solder wire, do not splice wires. reference air is drawn in thru wire sheathing. lots of folks online refer to it as "vented" wire or sensor wire air vent. you can use an extension with plug to extend wire but it is not ok to cut/splice wire to extend it. just get the right sensor.

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sensor was hard to unscrew. not a lot of thread left on old sensor. thread tips seemed to be rounded off. maybe sensor thread/female bung thread had seized up or fused over the years due to the high heat.

Edited by joeb
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had p0140 daily, p0141 sometimes and p1139 also sometimes. changed 02 sensor and today i get p0174. lean bank 2. but at least p0140 is gone. have newer intake gaskets. changed intake last year after damaging blow off flapper. have not really had any other codes in last year except for p0140. what sensor is providing the 0174 code? is it the bank 2 02 sensor?

Edited by joeb
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Something is causing a lean condition (vacuum leak) on bank 2, look for any vacuum hoses you may have knocked off doing the O2 sensor

Disconnect the battery?, to reset the PCM? Its possible that if you did not do a relearn, the PCM is fully compensated for the bad O2 sensor

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I always reset the CEL using the driver interface. so maybe it will settle down in the next day or so. maybe longer. the p0140 code is for a bad heater circuit in sensor. why would computer have issue with 1 of the 2 banks? wouldn't both banks be leaned or made richer together? or is car so sophisticated it can adjust individual banks? actually that makes sense. since each bank has its own sensor.

Edited by joeb
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I always reset the CEL using the driver interface. so maybe it will settle down in the next day or so. maybe longer. the p0140 code is for a bad heater circuit in sensor. why would computer have issue with 1 of the 2 banks? wouldn't both banks be leaned or made richer together? or is car so sophisticated it can adjust individual banks? actually that makes sense. since each bank has its own sensor.

Yes, the system has front and rear bank O2 sensors and it can determine a rich or lean condition by bank, something is leaning out bank 2 only. That could be intake manifold gaskets leaking on that bank.

If you recall, some NSs can get both codes (171 and 174) because the plenum between the TB and intake develops a leak, in your case something is only affecting bank 2. You mention intake gaskets earlier, why?, do they need replacing?

P0171 - Fuel Trim System Lean Bank 1

P0172 - Fuel Trim System Rich Bank 1

P0174 - Fuel Trim System Lean Bank 2

P0175 - Fuel Trim System Rich Bank 2

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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i did the heads 3yrs ago. did not replace intake manifold gaskets but the silicone ridges were flat. motor ran fine. 2yrs ago i had occasional miss. over tightened intake bolts and cracked intake. decided to replace intake with used one. put on new gaskets than. miss never really went away. fall, 2010 i put on new plug wires and miss seems to be gone but the p0140 code started showing up.

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