I have owned my 99 2500 for about a week and it is giving me the P1291 code. I haven't had a chance to drive it much, but notice that mileage computer says around 10mpg, which seems low. No trouble starting or running. Where should I start? Should I just change the IAT sensor once connections are checked? Should I change out the MAP sensor while I am at it? What is the best course of action to eliminate error code and improve mileage? What else should be looked at as possible mileage culprit?

Off the posted subject, but how do I get compass of CAL mode? It is not indicating correct direction at this time, and I have tried manual instructions.

Thanks for help!!
Steve

Update since this morning: Need four ball joints, axle seals leaking, tranny and engine leaking. Bought it as is so guess I will deal with it. What does a new tranny cost for this truck so I know how far to dig into fixing leak. It has 133,000 on it. Mechanic says he can probably fix, but should I maybe have a transmission shop look inside the thing before fixing leak? Look like I'll be busy for a while writing checks!

 

If you do get a new map sensor go to Hoesli Diesel about $65. From what I hear they seam to be reasonably common part to replace so you might as well if you are plannig on keeping it. Get the Edge Easy with th attitude monitor then you will have gauges too