Abs & esp lights r on & went into limp mode. RPM wax 3k but trans shifts fine. any idea?

First thing tomorrow, take it back to the shop that rebuilt it!!

you probably have a faulty abs sensor, the whole system gets information from the abs. If that sensor is reading improperly, it thinks the car is doing something it's not supposed to and it's reacting.

Is it not shifting into third gear (meaning you're at redline and the car won't shift), or is there not enough power to get the car going fast enough to warrant going into third gear? Have you checked to see if the car is in limp mode?

Check & replace if necessary the brake pedal switch placed above pedals on the support.
If the problem still occurs you might access the ESP & ABS ECU (Electronic Control Unit) using diagnostic equipment connected to the data link connector of the car, in order to pull out all DTC (Diagnostic Trouble Codes) memored.
Then you will be able to replace bad piece(s) and fix the problem by erasing all DTC stocked inside ESP & ABS ECU & reset it.
I'm convinced that your brake pedal switch is faulty because the glow plug warning light went ON, flashing and you can not take your ignition key out. Just replace the brake pedal switch, see if rear stop lamps light when press the brake pedal, and test the car on the road.
Two sensors are provided for engine starting authorization: The first one is placed on the automatic gearbox shift selector electronic module, which send a signal to the ignition switch barrel only if the shift knob is placed in park - "P" position, or in neutral - "N" position. Only now you can take out the ignition key from the ignition switch barrel. The second one is the brake pedal switch placed above brake pedal in the pedals bracket, which send a signal to the ignition switch barrel only if the brake pedal is depressed. Only now it is possible to cranking the engine by the electrical starter motor.

16619 -Engine boost condition - Limit not reached. Check intake hoses/ connections for leaks. Check Turbo charger waste gate regulating valve/ waste gate working correctly. Must move freely when accelerating, won't achieve full boost if waste gate sticking open. Check Turbo impeller turning freely, oil feed pipe for turbo can get blocked causing impeller to seize. Engine compact, not easy to access these components.

is there a CEL light on? (check engine light) if not it sounds to me like the audi went to safe mode. i need more details

I am having the exact same problem. The new sensor under the rear seat did not solve the issue. Does anyone have a solution?

Sounds like you have blown the fuse to this circuit.
Check you were supplied the correct bulb and replace fuse.

if the engine is running fine and no limp mode no engine lights. abs is working then the only other thing could be the dash may need replacing as putting the battery on wrong can blow the electronics in the dash as they are both linked. i ask is there any other problems as the rev counter work to ecu in line with speedo and the abs unit to determine timing etc. speedo works of the abs system the connection between them both is the board in the dash board. you can replace the boards in the dash but you will need replacement dash parts to do this but remember if you change the dash you need to log the miles as new dash will have different miles and uk mot log your miles to dvla. USA i dont know you would need to look into this.

I had the brake light switch replaced by a local dealer. Cost was $140 and it fixed the problem. Have driven the car for two weeks since and no lights and all systems normal.