I have a 2002 BMW 330 with a check engine light that goes on and off. The codes are PO113, PO171 and PO174 in that order. I also just had my valve cover gasket replaced that was leaking, not that they have anything to do with one another? Any ideas on what is causing this. Fuel pressure checked and found to be good, small vaccuum leak was also corrected but the light comes on and off still. Do these codes have to be "cleared" now? Thanks in advance for any advice.