I carried out routine oil change today, its the first time i have done the new shape myself, I Changed oil and filter no problem however on the 6 mile drive home a warning light came on that i can only descibe looks like an engine,, pulled over and checked oil level, all seems ok, The warning lamp is in the rev counter part of the dash,  is it a coincidence that the light has come on or could i have possibly knocked something when under the car, cant see anything odvious when i looked underneath.... Anyone have any ideas ??

i think that is emmissions light on facelift  :-/

Yep emissions light. If it's solidly lit then just carry on driving! If it's flashing your not supposed to use high(er) revs.

Had a spate of this on mine recently, diags showed 'CAT' threshold reached, had lamp reset 3 times over about three weeks, the last time it came on it went out a day later and hasn't been on since.

Thread here:-

http://www.omegaowners.com/forum/YaBB.pl?num=1190014479

Had this with my DTI, i changed the air mass filter, problem went away, I am not saying thats your problem but its worth checking.
Vx wanted £175.00 to supply and change, I got one off ebay for £25.00 brand new genuine part.

:y :y

looks like might have to go in for a check up, running a little lumpy today !!!