Experienced Limp Mode for the first time last night. Thought my car was broken for a sec.
 

I was giving a couple friends a ride and was accelerating onto the highway. I was intending to go WOT from 2nd through half of 4th, but it felt like it happened right before I shifted to 4th and after the shift I had no power. I was watching the tach and it felt like all of a sudden there was no power and I wasn't quite to the rev limiter. Slowed down and put it in 3rd and hit it and saw 5-6 PSI. Doh! Turned the car off and back on at the next exit and everything was fine.

On the way back it was perfectly fine. I forgot to turn off ESP, though, and it pwned me when I tried to let the tires loose in 1st and 2nd. Thought my car was broken again for a second till I saw the ESP light flashing...

VAG-COM showed no codes??? Strange. Running VAST sauce with a parallel MBC. It was 65F. Buddy said he was watching boost in 3rd and saw 22 PSI before he thought I left off. That *should* be close to requested so I don't know what the deal is.

That doesn't bode well for a trip to the drag strip :(

Jay, I had these same EXACT symptoms couple weeks ago. It is the N75 change that and..
 

you'll be golden.

I also had limp mode with no codes or CEL and after I restarted the car everything would go back to normal. Changed the N75 and everything is back to WOOT mode

whew scary. its got me before too!

I will do that. I have a new one among my inventory of S4 parts...

That will most likely fix your issue