How would I get Econ light to go off? I used carly diagnostic. But it couldn't clear code!

Would aircon re-gassing do the trick?

A regas may sort it but much more than likely your compressor has failed, the most common cause on these cars. When I bought my car cheap, with the econ light on, nearly eight years ago a simple regas sorted it for about 4/5 years though the well known pulley rattle was present (caused by perished rubber in the pulley). Since a new aftermarket compressor (around 250 quid) all has been fine. It is very important to renew the dryer, at the same time, which are around £15. 

Thanks. Basically reiterated what I thought. Will try self re-gasing and see if aircon pump clutch engages and Econ light will go off.

Mine done this and it was the pressure sensor at fault.

My Carly diagnosed this too thanks. Methinks I'll try a home regas to see if it clears it

Please keep us posted on how you get on