I have been getting a grey OBD code off & on for the last several months.
It does not set a dash light and it clears it's self in the cycle of the engine running.
I use the paid "torque app" to monitor my engine systems.
The code "P02FF"
I went to my dealer (Town ford in O.P. N.Y.) spoke with the manager and he could not find any results through his Ford system or the internet.
I also get some B codes with it mainly B0400

These all started after I had the Cam Phaser repair and Transmission fluid replaced back in April.
there have been some other codes that came up I cleared them and "most of them" do not come back.
these seem to happen when I'm towing or in a different Transmission mode AKA haul or sport mode.

 

I don't know what a grey code means.

I think you need to read the codes with Forscan to see what codes were saved. This will give a lot more information like actual code, why the code is logged, how many times it was logged, etc.

 

Just a guess based on a search.
P02FF converted from Hex to Decimal is code 767. That P code says transmission solenoid D is stuck.
The Bo4oo is a VCT solenoid sticking.
It appears these codes may be related to the work you had done.
Good luck.