Thanks for the reply, MadeInJapan. Actually, I have looked into this before, and have posted a similar question previously. My dilemma is that I do not know what defines a "drive cycle". All advice seems to point to two cold starts followed by a drive cycle to reset the computer. However, I have had at least three dozen cold, not so cold, warm and hot starts followed by a variety of driving speeds and distances. Alas, the problem remains.

There is apparently a very specific sequence of engine speed and time that will reset the computer. I don't know how long it will take for me to hit upon this in random driving, but I only have another 21 days until I have to pay for emissions testing again. The Volvo Dealer knows, but won't tell me, and it will cost me 1.5 hours of shop time for the Dealer to do it for me.

Perhaps my search of the archives has been incomplete, or I am using the wrong keywords, but I have not been able to come up with an answer to my question, namely, what exactly constitutes a drive cycle?