I just replaced the egr and oil cooler with Dorman parts (to save money), I am about to install a coolant filter system and I did a vc-9 coolant flush and cleaned the turbo and cleaned the intake manifold while I was at it, the egr valve was cleaned and seems to open up fine but i still get the p0405 code which I believe is that valve still not working so I have unplugged it this morning when truck was cold and it drives fine, but I also got the U1900 CAN bus communication code. Im not sure exactly what this one means, I have read up on it from several sites but still a little clueless on it. I did check all fuses by the brake cylinder and under the steering wheel (not sure if any more else where). Is there a particular plug or something I might be missing after doing all this work? The plan is to see how well this truck holds up since it does have 198,000 miles, if it proves to have no other issues I will spend the money on a egr delete kit and have the up pipe upgraded. So from what I gather as well is having the egr valve unplugged and once I have the coolant filter installed I should very unlikly have any issues with the new egr cooler correct? Sorry about the long post, this is my first diesel and I need it to last me as long as possible!

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Now its time to start on the little things like when my lights are on, the tach and turbo boost gauge dont light up at all and half of the speedometer light cuts out but a good slap to the dash fixes that.

 

Still no clue as to the U1900? Has anyone had this and found the solution???