high reving

[guest1185]

Our '52 plate jazz has started reving high, now the engine management light on the dashboard is on. Our local garage says the fault code is either the catalytic converter or the lambda sensor. The full exhaust was replaced six months ago so they changed the lambda sensor, it didn't make any difference, so they put the old sensor back in and didn't charge me. Engine light is still on and it is still reving high.
Does anyone have any ideas on solving this issue?   

[JazzyB]

I had a similar prob on a vauxhall nova, turned out to be the throttle position sensor. I would have that checked out first