I know the primary cause of this code could be a bad gas cap, but what are secondary causes specific to the Panamera that I should check for, if not the gas cap.
(I searched the forums, but didn't find a single P0455 post in the Panamera forum that discussed causes beyond the gas cap)
TIA

 

See this article. Replacement of the gas cap is inexpensive and likely to fix your problem. If you look closely at the seal/gasket, you may notice some micro-cracks/dry-rot. Replaced the gas cap on a 10 year old Porsche and it resolved my Check Engine Light.

 

What year and mileage? I would check the output of the vacuum pump and or see if you have oil in the vacuum line to the LDP.

 

Its a 5 1/2 yo 2012 with 76,000 miles on it.. The cap looks in great shape - tho I didn't put it under a microscope, so wanted to get a list of Panamera specific things to check. Where is the vacuum pump and line to the LDP.? (i've only had the car for a week!)

 

Turned out to be the vacuum line coming off the rubber adapter on the intake runner solenoid.....where ever that is!

Nice part was that the local Porsche dealer had mentioned last week the $160 charge to check the CEL, but at the end of the day, they didn't charge me a cent. (they did get $80 to program my second key that I purchased)

Happy, happy!

 

Good to hear. Sounds like you found a good dealer. $80 is actually pretty reasonable to program a key now a days.