Vauxhall Vectra C Elite 2.2 Z22SE
I had bad mis-firing with the EML and not knowing anything better I had my local garage replace the coil pack with a £160 non-GM one. But I still had the EML and the garage read the code to be the camshaft positioning sensor being out of specification. But the car seemed to be running OK so I carried on driving it with the light permanently on. 18 months later the car suddenly lost power and would only run slowly with no acceleration. At the time I had no option but to book it into my nearest GM workshop who diagnosed a blocked exhaust, caused by the catalytic converter all broken up inside. £740 later with a new cat the car was back on the road, but I still had the EML on. I took it back and the fitter read the code to be the camshaft positioning sensor. He was surprised and said the Z22SE engine doesn't have a camshaft positioning sensor (I didn't know this before), because its function is carried out within the coil pack electronics. He phoned Vauxhall Technical who told him it was a faulty coil pack. They also said the coil pack controls the timing at the spark plugs and the fuel injectors and the faulty one was probably the cause of the cat breaking up from unburnt petrol passing through the exhaust valves. The coil pack was then replaced by a genuine GM one for another £260 and the result was a revelation - smoother and quieter engine and improved petrol consumption. I learnt a lesson; only fit genuine GM parts. So after just recently paying out a total of £1000 the non-GM coil pack has been returned to the suppliers with a request to carry out diagnostic testing and consideration for a contribution to the cost. Although it looks identical to the GM one, I think the problem was caused by either a manufacturing fault, or that the design does not include the function of the camshaft positioning sensor which is the reason for the EML and error code. I am still waiting to hear from them.