Thanks everyone. This is an independent Volvo shop and one of the few shops around that seems to understand the 850, or so I thought. If anyone has recommendations in the Southeastern Massachusetts area, I'll listen. You're right, Klaus, I should learn to read the codes, and more. I am not mechanically-inclined (probably the big opposite) and thought I found a good shop to work with. And when the check engine light came on, I thought all it needed was a tune-up, which has been over two years, but these mechanics say it's fine and doesn't need one. I can see from all your responses that my thoughts about being taken advantage of this last time are likely right. About testing the parts: I've never been given the parts back after repairs. Should you ask for them? Sorry to be ignoramous-maximus, but I am grateful that lots of savvy people are willing to help on this Board. And glad so many of you have had good luck with your 850s! Take care.