NAC : Check engine reset on a Golf III ?

[Louis-Alain Richard]

I'm working on the 1998 2.0 Cabrio (honey's former ride, dad's actual) and
i've started the engine without the MFTS. Check engine light is solid : will
it go away itself after 20 restart or unplugging the battery ?

BTW, we replaced the engine in that car last week-end, and we did it so
perfectly that the check engine light did lit at all. Now, i've just
tightened a collar that was leaking a bit, so I unplugged that MFTS, and
bingo, a CEL ! 

Louis-Alain