hi I have had my engine managemnt light on on my audi a4 cabriolet sline 2006 1.8 turbo . did a diagnostic on my car and the follwing fault codes have come up. 17956 control valve boost pressure open circuit 17769 cyl 3 ignition circuit open circuit 16574 O2 sensor bank / sensor 17700 map controlled engine coding thermostat Can anyone please let me know if any of these fault codes are serious to fix mechanicaly and expensive job . the mechanic said the turbo is not kicking in due to one of the issues . He said that one fault code would of triggered all the others but not sure . does anyone know if i have a serious or expensive repair here please and if the parts to buy are any expensive . just thinking of the labour costs too different garages are quting me different prices to fix .