4
questions

due to key not being recognized by computer,my car only starts 1 out of 9 - 10 times. Sometimes disconnecting battery(which is new) helps but it appears to be getting worse. I'm told only vw dealer can fix it and its very expensive. Any advice?

The first Code(po234) is a turbo over boost I was told. My mechanic is not sure how to address the repair and I have a certain disdain for VW dealers so...the second code is exactly what your forum described it as. Again, multiple troubleshooting steps listed but maybe that list can be narrowed down some? My inspection won't pass until these codes are cleared, I just dropped a sum of money on rear springs/shocks. I am in need of help, please!

In the warmer weather it seems to run ok but not in the cold weather. My mileage has also dropped to 25 to 32 mpg, 32+/- warm weather, 25+/- cold weather. It's also slow to start when the temp drops below 40 deg.

my car starts just fine, but when i test out the volts level on the battery it says 12.31. what does this mean. do i need a new alternator? or is it something else?