Ok chaps I need your combined help my son In law ran the codes on my A4 2.0ltr Tdi SE it came back glow plug module (emissions light on ) I renewed the module cleared fault ,started the car engine cold it took about 20secs to fire , I did a resistance check on the glow plugs no 1& 2 191ohms no.3 & 4 .06 ohms so I changed all 4 with own parts .cleared the fault code again lo and behold emission light back on HELP