Volvo Repair: 940 Check Engine/Fuel Injectors, vacuum leaks, volvo drivers

Question
I recently bought a used 1994 4door 940 turbo.  There was a
check engine light on, and a repair place I took it to in town 1
said it was the fuel injectors and that they needed to be
"PowerVac"ed.  I had them do the procedure, so that I could
drive it 750+ miles to a new place, where I could not register it
with the indicator light on.  As I was in the middle of negotiating
on some pay back from the friend I bought the car from, I took
the car to a trusted mechanic in town A to get a second opinion
on some other expensive repairs proposed by the guy in town 1.  
He said that in all likelihood this "cleaning" procedure had been
unnecessary, which matched up with another very expensive
repair they had recomended on the power steering that turned
out to be bogus.  As in..completely.  Any thoughts on use of
"PowerVac" on the fuel system?  I'm no car expert!

Answer
Hello Rob,  Those systems were not to complicated, o2 and mixture codes are the usual suspects.Vacuum leaks can set off that lite.Volvo was never big on using alot of vac.hoses,so its easy to remedy any of them.She is older and o2 sensor do fail.Temperture sensors age and can set off that lite.There are codes to help find the cause.Find a capable Volvo guy and trust him/her yes there are 'Hers' out here.Talk to other volvo drivers,we're a neat bunch and will help any time we can!Good fuel and some DEX tron 3,1 qt. to a tank two times a year,before winter and before summer, and you'll be fine.Check out other Volvo club site for even more 'fun with volvo's' Thank you and good hunting!  PKD