Cadillac STS The newest installation of the performance sedan from Cadillac, having replaced the Seville

Just Recieved The Dreaded "Check Engine" Light

  #1  
Old 11-30-2009, 05:43 PM
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Default Just Recieved The Dreaded "Check Engine" Light

My 01 STS is just over 60,000 miles (100,000 kilometers).
Engine light just came on.
Pulled the codes.
"All" that came up were History.

Got a B1328 (RH sun load sensor fault /or/ Sys voltage greater than 15.9)
And a U1301 (class 2 short to battery)

Those are perplexing. But I dont believe they are the reason for the Engine light.

The other code is P0171 (Fuel Trim System Lean Bank 1)
I believe that may be my problem.
I have a guess as to what may be the problem. Im leaning towards an o2 sensor ?
Would that be a good guess ? Any other diagnosis for this code ?
 
  #2  
Old 11-30-2009, 07:41 PM
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Vacuum leaks are always the place to start with lean codes.
 
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Old 11-30-2009, 07:46 PM
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Thanx for quick reply slowroll.
The reason I was thinking a sensor is cause the code specified "bank 1"
So Im guessing that your saying even a simple general vac leak could also create a code that specifies a particular bank ?
 
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Old 11-30-2009, 08:44 PM
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Small ones can, location is a factor, larger ones will set multiple lean codes. O2 sensors do fail, but many times they are replaced under "Shoot the Messenger" logic. Unfortuneately scanner is required to monitor it's operation.
 
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Old 11-30-2009, 08:51 PM
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I have access to a scanner in the morn.
What should we be looking for ?
 
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Old 12-01-2009, 06:01 PM
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Monitor O2 sensor activity voltage should vary between .1-.9. also short term fuel trim should be near 0. O2 readings should not be fixed. post what you find
 
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Old 12-08-2009, 07:20 PM
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My buddy at work did not bring his scanner with him in the morn as said.
To tell the truth Im not even sure if he "Really" has an OBDII...He was really surprised that I was able to access the codes that I did from the OBD. Im guessing his reader is basically the same as the one built into my car....but thats besides the point now I guess.

Anyways....The next morn was the Tuesday. It was slow at work so the boss said Id could take of the next day (Wednesday). I said good cause I wanted to take my car in.
On the way home that Tuesday eve , right round the corner from my house ,The "engine light" went OFF.
I had the next day off anyways so I stopped by the dealer to inquirer.

Told him the light went on on Saturday. Didnt drive it Sunday.
Read my manual Monday so filled up the half tank after work with good premium.
Light went out after 30 miles/50k with the premium.
Asked him about maybe being a vacuum leak. Told me that light goin out after premium gas would/could point towards an O2 sensor. We discussed the two scenarios (me with the info Id gotten from this site) and I went on my way.
Seein as the light was out there was no reason for a $90 diagnostic. If the light came on again then I could bring it in and they would look at it. The Dealer I go to is really good. More so..The rep I talk to is aces. I talk to Dave and Dave only.

So I went out that day and Christmas shopped.
The next morn (Thursday) I was on my way to work. Was just up the road, hadnt got close to the highway and my boss called my cell. Said dont come in....no work....So I turned around.

I was at the same intersection that the light had come on and then again turned off when it came ON again. So I drove to the Dealer. They just opened.

Dave brought out the hand held and scanned my car. Originally I was Lean on Bank 1. Now It was saying Lean on Bank 2.
He had told me that a vacuum would generally create a misfire. So is why he "also" was leaning towards an O2 sensor. Seein as the car was running fine.
But with the hand held he saw that there was actually a "slight" misfire on 2 cylinders.
Nothing to bog down or anything. But was showing on the reader.

I left my car there for the day and he called me in the late morn and said I was right. Was A vac...per say....

Was the intake manifold. Had the front intake plenum replaced.
So basically it was deceiving. The O2 sensors were off. But was because of a bad seal.

With the information that I had gotten from this site. As well as using that info at the dealer. "WE" were able to pinpoint the problem without any bull. All was done sweet and simple with my car being in the shop for only half a day.
 
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