200tq check engine light, but no codes!?

[Ti Kan]

I don't think your car's ECU (MC-2 engine) has permanent fault
memory.  If the ignition is shut off, any recorded fault is gone.
So, to catch the fault, you should do your blink code check after
you encounter the check engine light, but before shutting off the
car.

-Ti
2003 A4 1.8T multitronic
2001 S4 biturbo 6-sp
1984 5000S turbo
1980 4000 2.0 5-sp
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Ivan Tuma writes:
> ...
> I recently put in the "missing" check engine light bulb into the cluster 
> so I could flash out error codes on it myself.
> I have noticed that after the car warms up a little, the check engine 
> light always comes on at ~3000 rmp corresponding precisely with the 
> occasional hesitation. It stays on regardless of engine load as long as 
> I stay above 3000rpm.  
> 
> If I try to flash out error codes, all I ever get is 4444 (no error) ... 
> even after I reset the flash (temporary pull of fuse #21) and a week of 
> driving. Is my assumption correct that knock sensor #1 is now starting 
> to go bad, just not bad enough to report a permenent error to the ECU? I 
> was expecting to see any of the following codes: 2141, 2142,2143 or 
> 2144, but so far none of these has shown up ... I did have some old 
> codes in there dealing with previose trouble (these I wiped out), FYI 
> they were  2123, 2312, 2214 and 2224 (none of these are related to knock 
> sensor problems however).
> ...