Can one bad injector be causing this 3 to 3.5 MPG?

Just a shot in the dark here but check and be sure the clutch fan hub is not stuck and keeping the fan engaged all the time. I just went through that on one of my trucks pulled the fuel mileage down quite a bit. On a side note I've never heard any thing good about the place you took your truck to.

 

I hope I didn't come off like an ### to you. I feel bad that they screwed you like that.

 

(mid128 sid6 fmi5) Injector 6 current below normal or open. It's probably in the injector wire harness itself, which is why I was asking if they actually took the rocker cover off before diagnosing a faulty injector. If I spent that much money on a injector and still had the same code, or same problem, I would find some other place to take it. Allot of times Volvo dealers see a fault code, and rather than investigating what caused the fault, they just start changing parts.

 

This is why I would never buy a volvo, their network of GOOD techs and shops is far and few.

 

Volvo motors are notorious for oil getting in the wiring harness. The dealer should have been able to diagnose that immediately.