Check Engine light comes on and I follow all of the steps to read the codes. I have a 1994 850 turbo wagon and I inserted the plug into the A2 socket. The only code I get is 1-5-3. I checked out the ozbrick site for the code meanings and there is no 1-5-3 for my type of engine. There is a 1-5-3 for the 10 valve non-turbo which is "Rear heated oxygen sensor signal". I also followed instructions to read all of the codes until they repeat and 1-5-3 repeats so it must be the only code. I cannot reset the codes even after following the instructions to the 'T'. Is there something unique about the 94 850 turbo engine diagnostic system that the site below does not mention?

http://au.geocities.com/ozbrick850/computercodesvolvo.html

Thanks for any help...