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Old 08-21-2007, 01:42 PM   #1
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O2 sensor questions

2000 Boxster

DME said that an O2 sensor is bad.

How long can I drive with a bad O2 sensor? What bad could it do to the car?

What does an O2 sensor do?

thanks,
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Old 08-21-2007, 02:06 PM   #2
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In crude terms, the O2 sensor senses the quality of the air in the exhaust. If too much air gets in (a lean condition - results in holing a piston) or too much gas gets in (a rich condition -not detrimental but not healthy either) the sensor notices it and this tells the computer how to vary the mixture to create an optimum condition.
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Old 08-21-2007, 03:26 PM   #3
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I just changed one of these this weekend. PRE-CAT Left. I got the CEL cleared it ordered the $120 Walker (Bosch was $40 more) 02 sensor from oxygensensors.com
The day before I was scheduled to put in the new 02 sensor I got the CEL again.
But this time there was CEL that said something about a big leak. Which I took to mean fix it today! Those catalytic converters are expen$ive to replace.
About four or five independent shops refused to swap in the new o2 sensor.
They wouldn't touch any manner of Porsche and another guy who had a classic Merc roadster sitting in the garage said they won't do it unless its a OEM Porsche sensor...grrrr... After about two hours of driving around I found a shop ONE BLOCK from my home. They charged me a full hour for the job $80! even though it was a simple Plug and play, you just need a lift to get at the sensors. but I wasn't arguing at that point the part had to come out. Guy did the job in 15 minutes and that was with allot back and forth presumably reading the manual.
He pointed out that the cords on the original sensor were long and the Walker had long cord. I called oxygensensors and they said its not an issue. Car sounded much better right away, quieter and smoother.
About two hours later I got another CEL (1276). I cleared chalking it up to the car not yet cycling the new information. So far so good. The original sensors are supposed to last 100K miles so replace them when they go bad. I'm wondering if I should have got the Bosch sensor if they last that long. The Walker is made by or uses Denso sensors.
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Old 08-21-2007, 05:32 PM   #4
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Your car is 7 years old and if it has 60k or more on it, you may want to save up and buy four new sensors and put them in. It's an easy swap and only take a half hour or so.

You'll quickly discover that the car will idle better, perform MUCH better, and increase your fuel economy. For my car, it was akin to getting a full tune up.
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Old 08-21-2007, 06:11 PM   #5
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@ Perfectlap,

Aren't you supposed to change out each set(left/right) of oxygen sensors at the same time?
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Old 08-21-2007, 06:40 PM   #6
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I did all 4 of mine and the maf. 90 dollars each at napa, you just have to build them.
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Old 08-22-2007, 06:54 AM   #7
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blinkwatt,
I was told that it's rare for all four to go at once and that replacing one in the same bank will not cause the other to fail. They are built to last 100K miles but my Boxster is on year 7 and I still haven't hit the halfway mark so I guess time is an issue as well. If you can pony up the $400-600 and have acess to a lift maybe its a good idea to do them all once but it doesn't sound like its really necessary. I think other forum members have changed just the one bad 02 sensor without any subsequent CELs.
p.s.
That $100 Actron OBDII reader is paying for itself. I saw the shop's pricing chart on the wall and they charge you $40 just to read and erase the CEL.
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Old 08-22-2007, 07:29 AM   #8
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Replacing one typically just throws another CE light and can cause poor fuel economy or a rough idle and even lousy performance down the road because of differences in the sensitivity levels of the older, burned sensors compared to the new, highly sensitive one. This is why Porsche recommends that all four are replaced at the same time.

I did not use a lift to replace mine. I used ramps and had plenty of room to work.

The oxygen sensor wrench tool is required as the space is just too tight to get an open ended wrench up into the space.
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