Just some research for you while mooching around the internet:
p1296
Change the coolant temperature sensor straight off. Ensure you buy a new clip and O ring seal with it. Possible some top up G12 coolant from VW in case you lose a bit. Open reservoir cap first to release any pressure then screw it back on tight to stop coolant draining out during the change.
P0507
Quote:
This DTC is more of an informational code, so if there are any other codes set, diagnose them first. If there are no other codes, inspect the intake air system for air or vacuum leaks and damage. If there are no symptoms other than the DTC itself, just clear the code and see whether it returns
P1136 = Long Term Fuel Trim Add. Fuel B1 System Too Lean.
There is likely to be extra air getting into the inlet that is leaning the mixture. As per code P0507 check for leaking/split inlet hoses first. Look especially at the thin black rubber vacuum hoses with cloth braiding on. These deteriorate internally, and split and are worth replacing anway. A length of hose is about $10 probably, cut to fit by yourself.
Keep us posted

, Ian