Could be many reasons. Assuming the check engine light is on, start with having the codes that are set read. That will help lead you to the cause.
Most VW's only go into limp mode if there is a very serious problem. Limp mode is there to protect the engine, not to be an inconvenience. To disable limp mode would be to allow the engine to self destruct.
Limp mode or (limp-in mode or limp-home mode)occurs when your computer in your car is not communicating with the sensors on your engine. On some cars(volkswagon Passat for example) If you disconnect the battery then the computer will lose all of the settings and will go into limp-in mode. The car will have little power and a top speed of only about 30 miles per hour. The function of limp-in mode is to get you to a place that can repair the car but the car is barely driveable.
You have to repair the cause of the code that put it in limp mode.
is limp mode is when you put the car on donks or on 3 wheels using hydrolics
fix the problom that put it in limp home mode then reset the computer
You have to fix the problem that caused the trouble codes that put it in limp mode.
enables limp home without damaging the engine.
Something is so wrong with the computer on the car that it gives up trying to manage the engine's performance and defaults all settings to a barely acceptable level that will allow you to limp the car to the garage.
Idle mode is when your computer isn't doing anything.
You have to repair the malfunction that is setting the code that has put the computer in limp mode.
It would depend greatly as to why it went into limp mode. It would have to be diagnosted first before giving a price.
The computer won't release it from limp in mode until the underlying problem is fixed and the trouble code cleared.