I recently installed Hypertech to my lly o4 duramax. Before I installed it I had 3 DTC codes. Can anybody tell me what they mean. The Codes are: P0670, P0675 and P1626. Before I installed the Hypertech I had removed the muffler and installed a straight pipe, however the Cat converter is still in place. The only other modifications were i replaced the 245 tires with 285 mud grips and I replaced the factory stereo with a Calrion aftermarket unit. Since the install of the hypertech I have noticed a lot more power "set to stage 2", however when the transmission changes gears there seams to be a pause and the a surge. Is this normal. Thanks for the reply's

http://www.autotap.com/codes.asp





hope this helps.

I had similar codes when installing the hypertech too. I also have 285's with a magnaflow exhaust system with the cat removed. The engine light never came on and I just reset the codes and never had any problem since. Remember, the trany needs time to learn the new found power so the shifts will be a little quirky at first. I have mine set at level 3 and have no preblems. I did however notice that when adjusting to tire sioze changes, the speedo is now off by 4 mph. It reads faster than I'm actually going. I dont get it. I might plug it back in and tune it for 31's and see if that works.

Did you actually measure the tires or did you just figure they were 33s? Some brands are different sized some reason. My tires measure 32.8 brand new... A little less now that they are worn a little... I thought the hypertech went by 1/4 inchs? If so you ought to be able to get it dead on.

Its an unwritten rule I guess that 285's are a hair under 33 inches. They're actually like 32 9/10 and 9 out of 10 tire companies round it up to an even 33's. I didnt measure them. I dont plan to either. I know how fast I'm going at any given time thanks to a GPS system that my wife aquired from the military. I just rotated the tires out yesterday and I couldnt believe the wear and tear allready. I have maybe 3-4000 miles on the tires if that many. Whatever. I guess its these discusting roads here.