Sorry...As great as Autometer's are for the money, you are looking at one of the sad side-effects of the proven gauges...It's a common problem with these...As far as I know, it's a goner 
It used to boost to 14psi, now its about 10. I have been told that 2 InHg is = to 1psi. I'll have to contact Autometer about sending it in....I've only had it 7mos so it should be covered. The car is put away for the winter anyways so.....toutsuu said:My question for you selser is what was it showing before you noticed it wasn't zeroing. I was always boost 12psi and then it started showing less and less and now it shows 7 and that is when I noticed it was -5 when off.
No, there should not be any vacuum if the motor isn't even running. Your guage is hooped as well.goodtimes11 said:i get like 2 hg/in of vacuum when i turn off my car. Is this Normal?