No 4th Gear Coupe SE Auto 2.0
 

I have a five year old SE Coupe, 2.0.Automatic.

It will not go into fourth(top) gear and when reached, it "freewheels" with the engine revving.

I can drive it with the overdrive button off, limiting it to third gear only.

Is the gearbox no good or, is it as I hope, the ratio sensors are faulty?

Any help appreciated

Phil