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help! annoying recurring CEL


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I have a recurring CEL I have been trying to troubleshoot without success.  The car is an '07 turbo, stock engine and exhaust, but I am told it previously had a protomotive tune (now supposed to be stock software).   It drives perfectly, no hesitation or mis-fire, but the CEL that appears every 3-5 drives after reset.    So far, the right side O2 sensors (leading and trailing) and MAF have been replaced in the past couple of months.   Recently, this was the status before I reset the light:
P2099 Post Catalyst Fuel Trim System Too Rich Bank 2
P2272 O2 Sensor Signal Stuck Lean Bank 2 Sensor 2
P2230 Barometric Press Circ Interm

P2227 pending Barometric Press Circ Range/Perf
P2198 pending O2 Sensor Signal Stuck Rich Bank2 Sensor 1
After that reset, the current code is:
P2228 (Barometric Pressure Sensor 'A' Circuit Low)
My original thinking was perhaps the barometric sensor itself, but I can find little or no information about it, other than that it may be on the DME itself.   I do have access to the durametric tool, which confirms no misfires at all.     Any and all suggestions much appreciated.
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2 hours ago, Loren said:



P2228 Function monitoring of torque comparison

Possible fault causes:
- Hot-film mass air flow meter faulty
- DME control module faulty


Thank you, Loren!   It is good to be back on the forum and enjoying Porsche ownership once more, even with an uncommon issue to troubleshoot.


MAF makes sense, as it was recently changed.  DME too, although I cringe at the potential cost to repair.     I don't understand the "Function monitoring of torque comparison"?    Is there anything I can log with the durametric that might enable me to tell which of the two possible fault causes is at play?



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18 hours ago, Loren said:



P2228 Function monitoring of torque comparison

Possible fault causes:
- Hot-film mass air flow meter faulty
- DME control module faulty


"Function monitoring of torque comparison" looks like ODB2 code P1508, that's not a code I have seen yet on my car.   Is there a correlation?  




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  • 3 weeks later...

Loren was kind enough to clarify for me in a private message, that these codes could indicate that the DME was expecting a different reading from the MAF than what it was seeing:




There is a mismatch of the reading from the MAF and the DME.

Try cleaning the MAF - use only MAF sensor cleaning fluid.

If that does not work then you will likely need to do further testing and perhaps replace the MAF.



Last weekend, after acquiring the 5 point pentalobe driver bit, I was able to remove and clean the right side MAF sensor.    The MAF sensor is new, recently replaced by Porsche, but start with the easy potential fixes first, right?    Today was the 3rd outing since the cleaning, and there had been no codes or pending codes on the previous two drives, so I was especially optimistic.    Unfortunately, I got the CEL again, similar circumstances to before.   Driving about 50mph, in 5th gear, with the engine at light throttle/coasting, I get the beep and CEL once more.   These familiar codes are:

  P2198                     O2 Sensor Signal Stuck Rich Bank2 Sensor 1
  P2228 pending        Barometric Pressure Sensor 'A' Circuit Low
  P2198 pending        O2 Sensor Signal Stuck Rich Bank2 Sensor 1
  p2099 pending        Post Catalyst Fuel Trim System Too Rich Bank 2


Before buying a MAF, what further testing is recommended?    I do have the durametric tool for diagnosis.



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  • 2 weeks later...

I cleaned the (right side) bank 2 MAF sensor and swapped it to the left side.   P2198 returned during the subsequent test drive, so the MAF sensor is not the issue.     Generic (non-Porsche) troubleshooting suggests


clogged exhaust

vacuum leak

faulty injector

fuel pressure       (but no reason this would be unique to the right side of the car)

bad O2 sensor    (but bank 2 sensors are new)


Multiple owners have suggested it is time for plugs and coils, but I've been dubious because the car runs beautifully and the durametric reports exactly zero misfires recorded.   I'll see if I can get bank 1 / bank 2 lambda values recorded.    Beyond that I may be doing plugs and coils.    Any suggestions much appreciated.





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  • 3 months later...

The problem turned out to be o2 spacers I had installed in the hopes of circumventing the catalyst efficiency check.   I removed the spacers and installed a 12k mile used muffler and converters, and most of the errors are resolved.   I am left with occasional P2227, P2228, and P2230 errors, all of which reference the barometric pressure sensor that I believe is part of the DME.    These errors sometimes follow a rough patch of road or railroad crossing, so I'm suspecting a bad component or solder joint.   Anyone know a facility that can work on the 997TT DME?



Edited by woody6
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