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OBD-II Codes P0172 RICH 1 / P0133 O2S SLOW 11

posted by  junkycosmos on  Tue Jan 4 13:50 CST 2005
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I appreciate any help here.

I've been getting a Check Engine Light for several months.

Originally I was pulling OBD-II codes of P0133 O2S SLOW 11. As this indicated the front Oxygen I was waiting to replace it.

However after driving for around 2months this code was replaced with P0172 RICH 1.

My understanding is that this code typically is caused by a vacum leak. However if I reset the OBD-II computer this code does not immediately return. Sometimes it returns after a day and other times after a week or more (often after it will return after driving the car fairly hard).

Here is where the mystery is. When using the car code software I can make the following observations:

#1 $03 Fuel System 1 and 2 Status is System 1 Closed loop but fault with at least one oxygen sensor - may be using single oxygen sensor for fuel control

#2 $14 O2S11 SHRTFT11 does show voltage adjustments varied with short term fuel trim that appear to change as expected with idle

My question: Doesn't #2 indicate that my oxygen sensors are functioning ? Should I be tracking down my vacuum leak or replacing the O2 sensor ?

1997 850 T-5 148K miles

Thanks in advance.







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    OBD-II Codes P0172 RICH 1 / P0133 O2S SLOW 11

    posted by  someone claiming to be bl on  Tue Jan 4 14:29 CST 2005 [RELATED]

    Is your mpg down like in the 12-15 mpg range and are you seeing black smoke out the exhaust? Went thru an identical fiasco with a 96 850 with the same codes. Turns out (1) had a vac leak and (2) recv'd the wrong 02 sensor followed by a defective sensor from a vendor. The front sensor was responsible for the codes and when we finally got it right, the car has been prefect ever since. Are you using Alex Peper's software? If so, configure your #1 gauge to read the voltage for the front o2 sensor (bank 1, sensor 1). Start the engine and watch the voltage. It will fluxiate quite rapidly in the .25-.75v range if the sensor is good.

    bl








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      OBD-II Codes P0172 RICH 1 / P0133 O2S SLOW 11

      posted by  junkycosmos on  Tue Jan 4 16:51 CST 2005
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      Thanks for the reply.

      I sure am using Alex Peper's software and I have good respect for it.

      From my log file I do see sensor $014 0S211 shift showing fast changes but I will have to try the guage setting you mention. I was thinking that the OS211 shift data (in the data tab) was the same but perhaps it is not ?

      I'm guessing I do have a vacuum leak as per what I read doing searches on P0172 RICH code.

      My mileage is still quite good I think ~ 22mpg with 75% freeway 25% street. No black smoke (just a brief/small puff if I floor it, which I wouldn't consider abnormal).

      The myserious part is that I do not get the P0172 code right away after resetting the computer .. (maybe it is an intermittent leak that only shows sometimes) ..

      I'm still trying to make sense of the other message I see in the data tab of "$03 Fuel System 1 and 2 Status is System 1 Closed loop but fault with at least one oxygen sensor - may be using single oxygen sensor for fuel control" ..

      Thanks again for your suggestion on guage setting!







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