SouthStreetTrader

Long term lurker. First post. Appreciate the value of the forum.

2013 S6, CPO(out of warranty), just rolled over 50k miles. Daily driver. Stock.

Two weeks ago I took the car to the car wash, then went to fill up with gas. Car off. Fill up. Car on and the alerts start coming on (No CEL):

TPMS error: Tire pressure: System Malfunction
ACC and Audi braking guard: Unavailable
Stabilization control (ESC): Fault! - see owners manual
Air suspension: System Fault
Sport Differential: System Fault

Car runs fine, no issue despite the alerts. Park car in heated garage overnight (car located in MN where it was likely around 0 degrees). Turn on the next day, all alerts are gone. Car is scheduled for a tire change the following day, bring car in and inform them of the code issue. Tires changed, dead LED in tail light fixed, and Audi says low voltage from battery caused the codes - replaces battery. Pick car up, runs fine, no errors. Drive 15 miles, park car outside of restaurant, come back an hour later, fire up and all the codes come back on + a solid color CEL.

Car has almost zero power when applying the pedal. Car must be moved as the parking zone becomes towable. Some snow on the ground, have to shovel car out of spot as all wheel drive not working. Minimal response to pedal. Car limps quarter mile home, chugging, pushing pedal further does nothing more. Car is being towed to audi today.

Any thoughts on what the issue could be?

Thank you.

SouthStreetTrader

Audi called today - CEL light was on when lot attendant moved it, but off when tech turned car on. Vacuum pressure code was available. They drove car for 20 miles and found nothing wrong. The car was not able to be driven and now is fine. The mystery continues.