So I replaced my CCU fan with a brand new original Porsche part in the back of the unit (fault code 45) and cleared the code using the Durametric tool. When I read the codes a few minutes later, fault code 45 is back. How is that possible? Is there a temporary vs permanent delete / clear function I am missing? Maybe I am not understanding this whole process as well as I thought.

As an aside- when I first read the fault code, I had 5 of them, cleared them, and was left with two. I replaced the fan (the old fan was dead) and cleared the code. I was left with one for a dead mixer flap motor I need to address. But why is the fan code coming back when I read the codes. All the other codes stayed away.

 

I guess you used the new original Porsche fan as replacement part?
As you have already found out, this fan draws a lot less current than the old one, and trips the fan fault detection circuit. I assume Porsche dealers does not know this.
The CCU can be adapted to the new fan current draw, but only by careful replacement of internal electronic parts.
Cheers,
Tore

 

Aha, thank you. Rather than changing components in the CCU, I will just ignore that fault code in the future when it comes back.