diag codes-idle switch

David G daveglu at hotmail.com
Thu Apr 16 20:32:10 PDT 2009

OK, spring's here, time to get stuff out.

I purchased a 91 200t 20v for an engine swap into my UrQ.

It runs fine, but in limp mode (1.3 bar boost).

So today I pulled codes and only got   2121 (Blink Fault Code), 00516 
VAG1551/2 Fault Code Number
Idle switch problem
Switch open circuit, stuck closed Switch defective (Internal solder 
connections intermittent) or wiring problem.

Is this a common problem, is there a repair?

I am thinking of putting the 20vt in the UrQ and bringing along the inj. 
I know probably should just go with the 034 and be able to bump the boost 
easily, but if I can get this running right, I think I could be happy with a 
stock boost 20v for quite a while.

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