I started up my truck this evening and the SES light came on with only 195 miles on the odometer. Went to the dealer real quick before they closed and had them read the codes. There were 3: Turbo underboost (however it passed on the most recent start), Engine coolant temperature fault (I cant remember the exact wording; but it failed on the last start), and some kind of a feul temperature fault (again cant remember the exact wording, and it also failed on the last start). When I start it, it goes into "cold mode", like glow plugs stay on for the max three seconds even though the engine was hot and it sorta high idles, like around 850 900 RPM for a few seconds. Im thinking the sensors are just defective and need replaced. Im gonna bring it back to the dealer tommorow and they'll fix it. I dont understand the turbo underboost code though, how would this be tripped if a coolant temp sensor failed? Anyone have any ideas?





BTW, temp gauge works fine, it must just be the temp sensor that reports to the ECM.

Hay Max I have had some similar problems. I believe the underboost code comes on anytime codes are set and then you exceed 3000 rpm. The truck protects itself after 3000 rpm for some reason. I had the same problem with EGR codes. I would clear them and if I exceeded 3000 the underboost code would set. Tried it 5 times. Every time I exceeded 3000 it would come on. If I stayed under 3000 no underboost code would come on. Good Luck. I have 05 also.