My check engine light is constantly coming on but no problem can be found.

Dealer said upgrade was installed and their invoice shows "installed 30677021-5 :ECM gasoline upgrade". Hope this helps. Only number I could find and hope it is "code number".

Usually to shop specializing in Volvo since dealer in my area closed. However, yesterday it was at a dealer to replace leaky fuel pump (extended warranty) and I was told they could check out the check engine light. After changing/upgrading codes and spending $100 light is on again; only drove 69 miles before it reappeared. Dealer says they will look at it again but it is extremely inconvenient for me to take it to them so may have to wait till next year. Meanwhile I'll just ignore it as car drives fine.

I agree with ABC below...if you can post any diagnostic info from the repair orders we may be able to provide some additional help.