Your generic OBD reader just scratches the surface of the car's memory. And it can't always interpret the Porsche codes correctly. If you are a serious DIY and plan to keep this car long term, then invest in a Durametric cable.
Contact the shop and see if they will give you a list of the code numbers and report back.
I had a similar problem to yours (recurring codes). My generic reader couldn't see a fault in the trans module. I was able to reset it with Durametric and was then able to set the car for the CA smog test.
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