Corsa engine light, emissions or VSS?

After researching on this website, about why my Corsa engine light refuses to shift, i have come across two solutions... both
are very different and can mean a big difference in price and labour for the old man, who apprantly is going to fix it.

My car is an X reg, 2000, 1 litre.

Engine light used to come on and off, now just stays on.
my exaust is fine, so does that rule out the emissions problem?
or the other solution is going into the dash board, and checking that the connectors are secure in the engine bay, does this sound a bit more likely?

help.... problem been going on for ages and no one seems to know how to help me..