My 1 year old Vauxhall Signum has developed a problem with the engine 
management warning light. It comes on when the engine is at 3500 revs and 
stays on until the engine stops and restarts. I noticed the problem 
particularly when towing my caravan but it happens solo if the revs go high. 
My garage has replaced a fuel sensor which the thought was the fault

Any ideas before I take it back to the garage on Wednesday?

Dave