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1996 Seville SLS
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Discussion Starter #1
Recently, when My water pump failed, the local Pontiac Dealer replaced it and checked the codes to see why my Service Engine Soon and Service Emission System Lights were displaying. They said I had a P0139 code. Power and Ground to Bank 1 Position 2 O`2 Sensor were OK, and that I need to replace the O`2 Sensor. Now, What is the function of this sensor and what could be the result of delaying the replacement until after Christmas (about 200 more miles). I had the engine serviced just before the sensor failure and it is running good. Also, is this a difficult sensor to replace so that only the Cadillac Dealor should do it since I can`t. I know a local mechanic who is an authorized Delco Dealer and is supposed to be good with Cadillacs, and Cheaper on parts and labor. Would you let him do it and what would be a fair price?
 

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White Diamond '03 DHS (with DTS floor shift)
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The O2 sensor monitors the oxygen in the exhaust stream and relays it back to the PCM. The PCM uses this info to determin fuel injector pulse width (how much fuel to feed the engine).

Bank 1 Sensor 2 is an easy one to replace. It is the pre-cat sensor.

You can probably do it yourself. You do need a special socket I believe. Really not much different than changing a spark plug.
 

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Cadillac Technician
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You can use a 7/8 open end wrench.
They are not too bad, provided they are not "stuck" in the pipe.
The new one should have an anti-seize coating on the threads.
 

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Ranger said:
The O2 sensor monitors the oxygen in the exhaust stream and relays it back to the PCM. The PCM uses this info to determin fuel injector pulse width (how much fuel to feed the engine).

Bank 1 Sensor 2 is an easy one to replace. It is the pre-cat sensor.

You can probably do it yourself. You do need a special socket I believe. Really not much different than changing a spark plug.
Oh yeah, definitely this is a do-it-yourself job if you have jack and jackstands (or ramps) and a 7/8 O2 sensor socket or open-end wrench as ewill3rd suggested. That's the easiest sensor to replace. It's right there in front of the catalytic converter, in the wide open and very easy to access. Just unplug the old one, unscrew it, screw in the new one, plug it in, and lower the car. Done. It's a 1/2 hour job start to finish. Anybody except oil change and muffler and brake shops should be able to do it very inexpensively. I would stick with a new Delco sensor instead of a Bosch. I have heard of problems with the Bosch sensors, but there are 4 of them on my car and they're fine at about 45k miles. If I have to replace any of them, I will use a Delco. They're actually a few bux cheaper anyway.

Let us know what you do and how it works out.
 

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1996 Seville SLS
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Discussion Starter #5
In my area this Delco sensor runs about $92 + tax and Bosch $62 +. Anyone know of a good, honest, cheaper place to order the Delco part?
 

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Caddy-O said:
In my area this Delco sensor runs about $92 + tax and Bosch $62 +. Anyone know of a good, honest, cheaper place to order the Delco part?
Try www.rockauto.com. They seem to have good prices and I've been happy with their service several times in the past. They also carry the Delco part and it is less expensive than the Bosch by a few bux.
 

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1996 Seville SLS
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Discussion Starter #7
During a discussion with someone at a auto shop about my replacing the Bank1 #2 o2 sensor, he asked if I had ever used BG 44K. He said that running a can through might just clear up the sensor problem if it just has carbon on it. I really don`t know how this would be possible with 44K, but I thought I would ask what you think. About ready to order the Delco Sensor.
 

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White Diamond '03 DHS (with DTS floor shift)
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Repairs in a bottle rarely work. Replace the sensor.
 

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Caddy-O said:
During a discussion with someone at a auto shop about my replacing the Bank1 #2 o2 sensor, he asked if I had ever used BG 44K. He said that running a can through might just clear up the sensor problem if it just has carbon on it. I really don`t know how this would be possible with 44K, but I thought I would ask what you think. About ready to order the Delco Sensor.
I think it would work perfectly! It would almost instantly remove the money from your wallet and put it in his. It will do nothing for the sensor, though.
 

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We use 44K here, but not to fix O2 sensors.
It's probably contaminated with something besides "carbon".
I'd still replace it.
 

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When you're 73 and not in the best of health, you don't replace sensors yourself.....Nobody answered Caddy O's question about how quickly that sensor needs to be replaced. Is it o.k. to drive 100 or so miles without replacing? Also, how do I get rid of the message in the meantime. I'll have the sensor replaced, but don't want to do it right away unless I have to, and the message scrolling is a little irritating. Any suggestions/answers? Thanks
 

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White Diamond '03 DHS (with DTS floor shift)
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I think you can drive it for a while with a bad sensor without doing any real harm. How you remove the message depends on the year and model, but if the sensor is really bad, the message will just reappear when the PCM detects a fault again. If it is intermittent, it may stay off til it is detcted again. That said, if it is intermittent, it will go out when the fault is not detected after 3 ignition cycles with no fault detected and the code will go into history. If your light is on constantly, then it is not intermittent and will reappear.
 
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