Vauxhall Meriva light keeps coming on

Ive had my car for 18 months now and for nearly all that time a light comes on mainly when going up a hill,its a car with a spanner which goes off when the engine is turned off,then after a few times of this light coming on another comes on,again when going up a hill and its an engine which does not go off.took it to the garage and had it hooked up to the computer and it comes up with a turbo problem,the mechanic resets the light so it isnt on,he says its a big expensive job 2put right.does anyone know if this is a job that needs to be done asap,the running of the car has not been affected by these lights although when pulling out of a junction it is a bit sluggish.