That's kind of unsatisfying, eh?
4521 is a Boost Pressure Actuator - Regulation too high, from what google tells me.
Interestingly they wrote 'tempering' and meant TAMPERING. I am guessing these are codes that might get tripped when somthing is used to fool the DDE into 'more performance'?
I think the tech (rightly) thought 'well, if the sensor isnt sending the right signal, that might be an issue...there have been recalls around this part. And PUMA isnt telling me to replace it, so maybe if I make up a dirty/brittle story, I can replace it for Mr RJ"
See what happens. Sorry, all I got
Keep it as simple as possible...but no simpler.