1990 A80 Q, Calif car, manual, Engine Fault Light ON

[ANDER,TONY (A-USA,ex2)]

I am a recent owner of a 130k miles A80 Q manual, Calif car.  
The Engine Fault Light comes on after anywhere from 5 to 30 
minutes of driving. It seems to come on sooner when driving 
uphill.  Turning the key off for a few secs makes the light 
go away, but then it will turn on again after 5-10 minutes.

Checked fault codes both with engine stopped and when the 
light was on and engine running and found nothing (4444.) 

I have replaced the fuel pump and filter and O2 sensor.
After the O2 sensor was replaced the light behaved (was off)
for about 200 miles, then it started acting up again...

Any thoughts appreciated!!!

Tony Ander
aander at newsignal.com, Colorado.