Hi there,
I recently acquired a 1993 A90 quattro (I have had to replace the fuel pump due to "wear") It was previously originally owned by my grandmother who kept it in great condition.

My question is:
The Check Engine Light comes on when I drive above 80 km/h (4th gear) and will stay on until the car is turned off. It does not come on unless I am on the highway. Does anyone know why this is happening? and what I should do?

Also, any advice on what to look out for with the age of this car? the winter coming? etc... Any advice is appreciated.

Thanks!