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Hi everyone! Long time reader - First time poster.

I have a '99 911 C2 with CEL on. Its reporting codes P1123 and P1125. Don't worry, Loren, I used the search feature and found a number of topics on possible issues that cause these codes. However, I have a unique issue with my DME.

I bought the car a year ago, and the dealer assured me the car was completely stock. BUT, no one can get the Porsche diagnostics computer to run tests through the DME. My car is being checked out at a Porsche-authorized dealer now, and they digress from giving me solutions to the CEL because of the DME issue (and inability to run diagnostics). They also said they tried to reprogram it back to its default with no success. They informed Porsche of the issue, hopefully they will hear back tomorrow.

Is it possible the previous owner unintentionally wiped the area of memory containing diagnostic functions by flashing the DME to change the engine mapping? Could the DME be the root issue? Or am I definitely in for a MAF and/or O2 sensor(s) either way?

Mostly just wondering if anyone has seen this type of issue before...

Thanks!

Brian

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:welcome:

Is it possible the previous owner unintentionally wiped the area of memory containing diagnostic functions by flashing the DME to change the engine mapping? Could the DME be the root issue? Or am I definitely in for a MAF and/or O2 sensor(s) either way?

I doubt that could have been done with a PST2 or PIWIS - more likely a 3rd party re-programming tool.

I have seen DME's trashed (made unprogramable) by a bad 3rd party flash.

You need to see the MAF readings at idle and 2500 RPM to see if it is a bad MAF or some other problem.

It is not an O2 sensor - those faults say your mixture is so rich the DME can not make it lean enough.

Where are you located?

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Heard back from the dealer, they confirmed the MAF being the most logical place to start, so I gave them the goahead to slap a new one in. He mentioned they aren't going to clear the codes to see if they go away within a drive-cycle. So, exactly what is a drive-cycle in late model Porsche? There must be some criteria the engine management system uses to determine when a drive-cycle has been completed.

Oh, and the DME is helpless... new one installed is $2200 :(

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Heard back from the dealer, they confirmed the MAF being the most logical place to start, so I gave them the goahead to slap a new one in. He mentioned they aren't going to clear the codes to see if they go away within a drive-cycle. So, exactly what is a drive-cycle in late model Porsche? There must be some criteria the engine management system uses to determine when a drive-cycle has been completed.

Oh, and the DME is helpless... new one installed is $2200 :(

When all is done I would take it to another dealer and see if they can read the DME. The dealer near me did it all wrong and thought I had a problem also until someome told them how to use the tester.

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When all is done I would take it to another dealer and see if they can read the DME. The dealer near me did it all wrong and thought I had a problem also until someome told them how to use the tester.

Good point, mother. Yes, this is the 2nd dealer. The fault code first registered last fall, so I brought that up with the first dealer when it went in for an oil change before storing it for the winter. They were the ones to first bring up the DME issue. I gave a heads up to the dealer I'm currently working with, and they confirmed it. The first dealer also used the tester on another 996 that day just to confirm the problem wasn't the tool.

But, regarding the lean-threshold p-codes, I had the car out briefly and feels a bit smoother with the new MAF sensor.

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  • 4 weeks later...
  • 4 weeks later...

Hey I just read this and since I too am in 'the burg" was going to offer my ECU for you to swap in to see if it was related to your other components..but glad it's all sorted now. I have a '99 C2 as well that I use when instructing up at BeaveRun... have you tracked your car yet? I have an incar video from BR on my blog if interested.... Apex996.blogspot.com

cheers!

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  • 2 weeks later...
Hey I just read this and since I too am in 'the burg" was going to offer my ECU for you to swap in to see if it was related to your other components..but glad it's all sorted now. I have a '99 C2 as well that I use when instructing up at BeaveRun... have you tracked your car yet? I have an incar video from BR on my blog if interested.... Apex996.blogspot.com

cheers!

No I haven't tracked the car YET, but I've always wanted to try my hand at a circuit. It looks like great fun. Are you active in the local PCA? I recently joined but haven't made it to any club functions or met anyone so far. I am hoping to make it to BeaveRun or Mid-Ohio one of these days.

I checked out the in-car video and the dyno test, is your C2 purely a track car? It sounds great!

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