how do i fix the automatic choke renault scenic 1.6 1999?

i have a renault scenic and i think the auto choke is sticking lumpy idle ,excesive fuel usage ,lack of power etc. the car is regularly serviced with about 72000 miles on the clock. there is a yellow light on the dashthat comes on 10 seconds after starting its a box with a wavey line through it help any other ideas?

brian hitchings
May 2006