Overboost code?

[Redbox]

Hi all-
I've been getting an over boost situation on my stock 04 v70R. Gas mileage has been getting worse, so I changed the upstream O2 sensor and put new plugs in, but no improvement. The other day I punched it and just happened to glance at my boost gauge and it was at about 18 and rising. Got off it and have stayed off it since. Car runs fine with no other issues (other than the mileage). I figured I knocked a hose loose someplace, but have yet to find anything. I have not set up my VIDA system yet, but can scan with a basic OBDII scanner. So, the question is, will an over boost set a code? No CEL or anything showing currently. 243,000 miles, well taken care of.

Thanks for any help.