QuestionI have a fully serviced Vauxhall astra with 54,000 miles on the clock and for the past 3 months it has shown an exhaust emmission warning light at least once a month.
When it is 'plugged in' it shows 'Misfire on Cylinder 3'.
So far, it has had new plugs and a new coil pack yet the problem still exists.
It is now presently at a main dealer who casually stated that 'it needs a new ECU'.
When pushed to confirm compression results all I was told was 'they were fine'.
The questions I have are:
What could possibly be the underlying problem which is causing the emission light to come on?
What else could be checked before I even consider changing an ECU?
Any and all advice / assistance you can give would be VERY mich appreciated.
AnswerHi Steve, it is possible for the ECU to be faulty although it is rare. Check the lambda sensor (as this can cause a lean misfire) but that would not explain why cylinder 3? You could buy a used ECU from a scrap yard for around £50-£80, but I can't recommend any because I don't know where in the country you are. Did the garage clear down the trouble codes after fitting the coil pack/plugs? Lastly it is possible that you have purchased a faulty coil pack (this rare and infuriating anomalie can occur and cause untold problems because the mechanic then looks at other things, assuming that the new part is working) hope you get it sorted - good luck - paul
