I own a Zafira GSI (Z20LET no EDS Phase II, ppipe and all...) and I just fitted an Autometer EGT gauge. The gauge works fine for the first 10-20 minutes then it goes all over the place and stabilizes to 400F. It may come alive again some times. I noticed that when I switch off and go for a ride (after it has really cooled down) the gauge is ok and then the same problem appears..
Do you know of a cure? Is it bad wiring? Is it some kind of interference that has to do with temp as well????
Thanx for your help