Any advise welcome. Astra h 1.6 petrol runs rough, immision light comes on and shows error code 035100. So far as I have found this means coil fault. I took the coil pack off cleaned it put it back together and it was ok for a few weeks but did it again, put new plugs in, ok for a few weeks again but its done it again, same simptoms. A quick clean and its ok. Do I need a new coil pack or is it somthing other than the coil? Thanks Steve.