I'm throwing a 0118 code which is the high circuit. I replaced the sensor on the rear of the head and lower radiator. Started it up, same issues of constant fans, will not operate over 150*, reads cold on the factory gauge, normal boost for turbo is 9-10lbs, now in "limp mode" will only hit 4-5lbs. It's really frustrating. I just did the thermostat early summer. But always possible I guess.
Coolant sensors, low boost, constant fans. on 2003 Audi A4 Quattro
Poss. wiring issue , or faulty PCM.
seek help these can be very diff to diag and repair at times.poss thermostat stuck or even impellars on water pump are rotting away this is very common as they are plastic. most likely water pump