Hi got a 2013 Vauxhall insignia 2.0 cdti Sri and only owned it a month was ok but last Friday the service vehicle soon came on driver info , got a scanner but said there was no codes and everyone said there should be codes so had to get mobile mechanic to come out and he read codes and there was one for glowplug 3 so got to change that but cannot understand why my scanner wouldn't pick it up suppose to be for Vauxhall insignia

Could be blocked DPF, quite frankly these engines are crap for short town like driving, awful design! You might find this topic useful, your car may also go into limp mode when you get this message/light/warning - https://www.vauxhall.co.uk/help-centre/owners/cleaning-my-diesel-particulate-filter.html