hi need help my audi q7 is poor at staring when cold ive been told by audi it could be one of 3 things but they are not sure its either glowplugs injector or starter motor the only problem is they cannot comunicate through obd to get a code so if any one has had this problem i could use some help thankyou

My Q7 was intermittently taking a while to start (10 seconds then a puff of white smoke when started) diagnostics showed the number six glow plug was the problem. Only £17 from euro parts so put a full set in and has been fine since. Was told that because it didn't fire straight away that unburnt fuel was getting to the lambda sensor and so the ecu was backing the fuel off hence why it would just turn over and over.