Boost guage suddenly shifted 20 units
I have a 2012 WRX and admit that I don't have a strong working knowledge of how the turbo boost guage works. Here's what I do know. Typically at idle the boost guage reads 20 inHg and upon accleration the vacuum level drops down (depending on how hard you get on it) to 0 inHg and eventually the boost kicks in and the guage shows the boost in psi.
Just the other day when I started her up the baseline was bottomed out below 30 inHg (as seen in the picture). It appears to still work because when I accelerate the vacuum drops as it did before but everything is basically shifted by 10 units.
The car doesn't seem to be driving any different but the temperature in Chicago has been -10 for several days so I haven't really been driving it very hard. The only potential culprits I see are 1. the extremely cold weather we've had. 2. I hit a ridiculous pot hole the other day that rattled my teeth.
Is it possible that something on the guage popped loose or more likely that there is an actual problem with the boost? In normal casual driving would you notice a difference if the turbo was not functioning correctly?