I drive a 90 CQ 20V and I'm having this problem with my check engine light coming on at 3500ish RPM's, It's fine under 3500 but as soon as it hits that point the check engine light comes on until I turn off the ignition then back on again and I don't see the light again until I push it to 3500. I am pretty new to Audi, I searched the forums and couldn't find this same problem. Any Advice???

 

You'll need to have the codes read.