Overboost and baro pressure high

I am experiencing codes P0234 AND P0108 intermmitently. Surely if it was a real mechanical problem it would come up all the time? So I'm assuming it's a fault in the electrical warning system. I replaced the MAP sensor some etime ago and it was OK for a while. I found the turbo wastegate lever was sticky so I cleaned the turbo out and now it works smoothly. The other day it did around 80 miles with some hard acceleration but then at low revs when I backed off the throttle it came on again. It sometimes shows overboost and sometimes just excess baro pressure.

Any ideas will be helpful thanks.

Overboost and baro pressure high