Hi All. I hope someone can help! I am a newbie Diy'er. I have just serviced the vihicle, incuding oil / filter / air filter / sparkplugs. It is a 2.0 TFSI A4 (2006) with 90K on it. I have a set of error codes that have come up a few days after the service (possibly unrelated). They are... 17026/P0642/001602 - Sensor Reference Voltage A: Circuit: Low 19593/P3137/012599 - Intake Manifold Runner Control: Basic Setting not Completed 18693/P2261/008801 - Boost Pressure Control Valve (N249): Mechanical Malfunction P000A/000010 - Camshaft A (Bank 1 Intake): Positioner Slow Response Any ideas where I should start? Could the coils have been damaged whilst replacing the sparkplugs? Which item is most likely to cause this sudden line-up of issues? Intake manifold perhaps? Should I reset the errors and see which ones come up again? Any advice would be greatly appreciated! I'd hate to go on a wild goosechase when there is a single likely solution!