For me, I had to disable the immobilizer in order to establish a connection to the DME... Perhaps this link will help with the reported code.

https://rennlist.com/forums/993-foru...code-help.html

 

Attached is the factory document, I believe listing all the codes related to the 993:

• 26 Oxygen Sensing, Area 2 P1127 P1128 2 cylinders (1-3)
• P1127 = Version 3 Short to Ground / Below Lower Limit / Lean Mixture Limit
• P1128 = Version 4 Short to B+ / Above Upper Limit/ Rich Mixture Limit
• 2 Malfunction Indicator Light (MIL) is on and a previous Freeze Frame is overridden

First I would clear the code and see if it returns as if it is truly a running condition the diagnostic code should reappear.
It can be one or both of your oxygen sensors on the driver side of the engine is out of specification It may be the nomenclature "Area 2" above refers to the before or after catalytic converter specific oxygen sensor narrowing the problem down. Other Rennlisters may reply to your posting with the answer to this.
OR
You have something causing mixture problems on the driver side of the engine (Cylinders (1 through 3) only.
If the running data from each of the oxygen sensors seems reasonable the possible causes could be:
A vacuum leak as if it was an overall issue I would think it would impact both sides of the engine.
Sometimes an analysis of the oxygen sensors can seem inconclusive so if your oxygen sensors on that side of the engine have never been replaced I would just replace them both. No need to buy the Porsche branded part as BOSCH is the OE supplier and the aftermarket BOSCH branded part is the same part. It is an easy DIY. The key is to use a little penetrating oil on the sensor mount, cut the wires to it and slip a closed end box wrench over the sensor to crack it loose then fully screw in the new sensor in and then use the old sensor's cut wire to fish the new sensors pigtail up to its socket on the driver side engine compartment
wall.
Andy

 

As pointed out above by nine9six the immobilizer must be inactive for the OBD connection to work so it can work with the engine on or simply the ignition on as long as you opened the door to you car first using the electronic key fob and in the process deactivated the immobilizer. The immobilizer is inactive when the little picture of the key fob in the clock is not illuminated.

 

 

Very odd as unlike my 96', maybe a feature of your Motronic controller software version.
Andy

 

For me as well... my car has to be running to scan.