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Old 06-05-2013, 10:24 AM   #1
Benny Minn
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SES light goes away after having car detailed

I had the SES light on for a week with the error code that reads: "Oxygen sensor voltage after catalyst bank 2, open circuit." Yesterday, I had the car professionally detailed, including the engine bay, and when I picked it up, the light was off. Coincidence?
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Old 06-05-2013, 10:52 AM   #2
scarede46er
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Yes.
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Old 06-05-2013, 10:53 AM   #3
white46
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Yes +2
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Old 06-05-2013, 11:29 AM   #4
jcns
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check the O2 sensor. If it failed, it defaults to rich. If it runs rich too long, your cats will be gone too.
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Old 06-05-2013, 12:38 PM   #5
Benny Minn
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check the O2 sensor. If it failed, it defaults to rich. If it runs rich too long, your cats will be gone too.
I ordered new post-cat sensors a few days ago and I have noticed that the gas mileage seems low, so I'm sure they're dying if not already completely dead.

Last edited by Benny Minn; 06-05-2013 at 04:49 PM.
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Old 06-05-2013, 12:45 PM   #6
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The car just wanted to be cleaned. thats all.
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Old 06-05-2013, 03:06 PM   #7
jdstrickland
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Originally Posted by jcns View Post
check the O2 sensor. If it failed, it defaults to rich. If it runs rich too long, your cats will be gone too.
EXCEPT that the error is the Post CAT sensor, which will not make the car run rich, or lean for that matter.
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Old 06-05-2013, 03:32 PM   #8
Benny Minn
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EXCEPT that the error is the Post CAT sensor, which will not make the car run rich, or lean for that matter.
So, the post-cat sensors are just there to verify that the cats work? If so, it sounds like I should have ordered the pre-cat sensors too. Ugh. I wouldn't mind so much if these cost half as much as they do, but I'm starting to miss my single-sensor M50.
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Old 06-05-2013, 03:35 PM   #9
TrickTizzle
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SES light goes away after having car detailed

You should of bought post cat sensors. Or try to find a local that know what they're doing with a GT1 who can reflash your ecu/dme with the EU2 tune which turns off post cat monitoring.


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Last edited by TrickTizzle; 06-05-2013 at 03:35 PM.
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Old 06-05-2013, 04:40 PM   #10
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Originally Posted by Benny Minn View Post
So, the post-cat sensors are just there to verify that the cats work? If so, it sounds like I should have ordered the pre-cat sensors too. Ugh. I wouldn't mind so much if these cost half as much as they do, but I'm starting to miss my single-sensor M50.
You're confusing yourself, and me.

You said you had codes for the Post CAT sensors, why are you replacing the Pre CAT sensors?

The Pre CAT sensors look at the exhaust stream and evaluate the contents for the amount of fuel contained, if there is too much or too little then the computer will adjust the fuel trim accordingly. If the sensors detect too much or too little fuel in the exhaust for a long enough period of time, the computer will throw a code to tell you that the fuel mixture is rich or lean, or that it is having a malfunction if it is alternating between rich and lean.

The Post CAT sensors look at the exhaust and compare what comes out of the CAT with what went in, and see that it is cleaner.

The fuel ratio needs to be 14.7:1 so that the molecules can be evenly combined to produce clean air and water. Without getting overly technical, the exhaust goes into the CAT and the various molecules can be split and combined through heat and the molecular components of the CAT itself to produce basically water and oxygen.

The Post CAT sensors verify that the chemical change from dirty stuff to clean has taken place. THAT IS ALL THEY DO.

Last edited by jdstrickland; 06-05-2013 at 04:40 PM.
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Old 06-05-2013, 04:57 PM   #11
Benny Minn
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You're confusing yourself, and me.

You said you had codes for the Post CAT sensors, why are you replacing the Pre CAT sensors?
I realize I worded that last message in a confusing way. To clarify, I have not yet ordered the pre's. Earlier in this thread, I said that I had new sensors on the way to alleviate the recorded SES error. Those are indeed the POST-CAT sensors. However, later in the discussion, it sounded like two things are likely:
1. If the post-CAT sensors are old and dying, then it's likely that the pre's are entering the end of their useful life-cycle as well.
2.The Pre-CAT sensors failing could likely cause the lower-than-expected fuel economy that I believe I'm seeing.
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Old 06-05-2013, 05:02 PM   #12
jdstrickland
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Originally Posted by Benny Minn View Post
I realize I worded that last message in a confusing way. To clarify, I have not yet ordered the pre's. Earlier in this thread, I said that I had new sensors on the way to alleviate the recorded SES error. Those are indeed the POST-CAT sensors. However, later in the discussion, it sounded like two things are likely:
1. If the post-CAT sensors are old and dying, then it's likely that the pre's are entering the end of their useful life-cycle as well.
2.The Pre-CAT sensors failing could likely cause the lower-than-expected fuel economy that I believe I'm seeing.
THAT makes sense. I concur, doctor.
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Old 06-07-2013, 01:30 AM   #13
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I remember having the "Oxygen sensor bank 2 lean condition" pop up on me last summer so I went online and ordered two pre-cat O2s. A few days later the SES light went away and has never returned. On our cars, the post-cat O2s hardly ever go wrong so don't bother ordering these.

So now I two pre-cat O2s lying around waiting to be installed once I get off my lazy ass.
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Old 06-07-2013, 01:34 AM   #14
Benny Minn
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Originally Posted by TopazBlu02 View Post
I remember having the "Oxygen sensor bank 2 lean condition" pop up on me last summer so I went online and ordered two pre-cat O2s. A few days later the SES light went away and has never returned. On our cars, the post-cat O2s hardly ever go wrong so don't bother ordering these.

So now I two pre-cat O2s lying around waiting to be installed once I get off my lazy ass.
This might have been helpful advice IF:
1. I hadn't already ordered them a week ago, and
2. if the light didn't come back on today, which it did.
3. if the error was a lean condition and not an "open circuit" condition.- different error than what you had and for different sensors.

Last edited by Benny Minn; 06-07-2013 at 01:39 AM.
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Old 06-07-2013, 06:36 AM   #15
dknightd
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Could be a bad electrical connection. Detailing (washing engine) might have cleaned up enough to make temporary contact. You might try just disconnecting sensor, cleaning connector, then reattach.
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