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Old 03-08-2007, 01:02 PM   #7
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Join Date: Sep 2005
Location: Minneapolis/St. Paul, Minnesota, USA
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Quote:
Originally Posted by CJ_Boxster
They are both OBDII, but on renntech.org, they have 2 different OBDII sections... one for MY97 - MY99, and one for MY00 - MY04 so i assume the P codes might differ slightly. In your case, its the same error message either way.
Hi,

Nope. The OBDII Codes are a Standard created by the SAE (Soc. of Automotive Engineers) - they are the same. They are properly referred to as DTCs (diagnostic trouble codes) and are all 5-digits.

Within this mandated Standard, a Manufacturer has the ability to set proprietary codes or sub-codes, meaning that a generic DTC can have multiple meanings albethey related. The 1st digit identifies the type of code. There are 3 variations: 'P' (Powertrain), 'B' (Body) and 'C' (Chasis). A 'P' code means that it is powertrain related.

The next digit identifies the DTC as either an SAE code or a Manufacturers proprietary code or FCs (Fault Codes). This will either be a 0 - SAE or 1 - Porsche specific code - FC.

The 3rd digit refers to a specific System or value within the DTC type. 0 -Total System. 1 - Air/Fuel Induction, 2 - Fuel Injection, 3 - Ignition System or misfire, 4 - Aux. Emissions Control, 5 - Vehicle Speed/Idle Control, 6 - ECM Input/Output, 7 - Transmission.

The final digit refers to a specific component or condition within the defined System.

So, the code P1275 means: P Powertrain, 1 Porsche subcode, 2 Fuel Injection, 5 Pre-catalyst O² Sensor, Bank 1-3.

Now, the software version of the ECU (DME in Porsche Speak) allows for greater/lesser subgroups based on it's sophistication and memory. Version 5.2.2 allows fewer specific parameters than does version 7.2 or 7.8.

To read these subgroups, you need a Porche specific code reader (PST2 or PIWI). But, several lists of these codes are available through any number of sources such as the Workshop Manual or the Bentley Service Manual.

Code P1275, Posche FC 16 for Bosch Motronic 7.2, indicates that this is an aging O² Sensor on Bank 1-3. Clearly, this is not the case, You have now reached the limit of what the onboard diagnostics can tell you. So one must look at why the DME is indicating this fault or why the sensor itself is emmulating an aging sensor.

My intuition and awareness of past similar problems tells me that the most likely (but certainly not the only) possible cause is that the pre-cat and post cat sensors are not properly spaced apart, or that the new Cat is incapable of flowing as well as advertised. Long distance diagnosis is difficult at best, but this is where I'd start. Hope this helps...

Happy Motoring!... Jim'99
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