check engine light

[george]

o.k. mine is 1990 525 i 190,ooo miles . has been slight rough idle of late but smoothes out when warmed up, now i ve noticed red check engine light come on brieflly. what should i be looking for or what does mean?

[shogun]

If the rough idle is smoothing out when engine is warmed up, I would at first look for air leaks. Material expands when it gets warm and that closes air leaks on cold material.
Also check the temperature sensor in the air intake system.
I assume that you are regularly changing spark plugs, distributor cap and rotor. If not, check them too.
If you have a US specification car, you can also do a stomp test to see details. Stomp test and the details are on my website below explained.