Ive got a 1999 astra 1.6 16v (X16XEL model I think) and a few days ago the engine electronics light came up as I was driving the car.
Ive since done the paperclip test and its showing a P0170 fault (Fuel Trim Malfunction).
When travelling around at say 30-40mph the light does not come on. It only appears when Im travelling at higher speeds (say 50 or 60+ mph) and then, only after a minute or so of doing that speed. Ive also noticed that I can travel at 60-70mph without the light coming on at all if I take my foot off the accelerator every few seconds, so it seems that only moderate to higher throttle use for slightly prolonged periods triggers the light to come on.
From what Ive read so far, some form of air leak (intake or exhaust) or faulty 02 or MAF sensor are the main culprits.
I don't have much in the way of expertise with cars, nor do I have a garage full of tools to do loads of my own repairs. However, before I go taking it do a dealer and giving them my hard earned cash, anyones thoughts on simple ways to narrow down the likely causes, or just my best course of action from here would be appreciated.