Had intermittant loss of power on wifey's Astra which turned out to be the coil pack but this doesnt usually put the eml on because the fault is in the secondary windings and only the primaries are monitored by the ecu ( or can the later s/w detect misfire by listening to the knock sensor?? TB ? )
If eml has been on then there should be fault codes stored, get these read and cleared. If there is just one stored then work from there, if several these could be old problems so you will have to wait for the light to come on again and get it re-read to find out the current problem.
When i put a faulty coil pack (on purpose) into my VeccyC after a few misses the EML came on.....tho i didnt read the codes, but i suspect they would probably say miss fires detected.
If youve recently changed the plugs on it.....you would have noticed if the plug wells are filling with oil......this was the cause of my 2.2 missing recently.....if you carnt get the codes read cheaply, tho worth getting a cheap code reader as you will probably use it at another time....i would go for the cheap option of changing the plugs again.....just in case one is breaking down (also will see if oil in the plug wells) then if no different go for the coil pack
