I just posted a reply to the same problem on April 26. Same thing happened to me, ratcheting the shift lever didn't solve my problem. I had to replace the PNP switch, mostly a tedious effort to gain access. check out Bay 13 for instructions, they are very complete. Suggest you consider buying the Pocket Data Booklet directly from volvo, the part number is TP 0302207. I think it is about $15. It covers all the codes not just the popular ones (I got stuff that wasn't listed in the Haynes manual). If you're going to mess with your engine, you need this book! Where else can you get the info on how much resistance between pins 1 & 4 indicate a good MAS? (110 ohms).