So I went to get my trany flushed yesterday, and in the process of the shop flushing it a hose blew on the machine and frying there machine and pumping a bunch of fluid out of my trany. So they fill it back up and try to give it back to me but I get in it to drive away and the “service engine soon” light is on. So I tell the guy and tack it for a short drive to see if everything feels ok, get back still on so they try and plug in a code reader and get nothing, no power. So the question is, is the trany guna be fine with having that much fluid pumped out of it while running, and can you not use a regular OBD II on the Duramax? And sorry if this needs to be in the trany section but my main concern was the OBD II port not working that’s why I put it here.

Check your lighter and aux ports. I think it is on the same fuse.

take the mater up with the trans shops mgr. and tell them they will be resposible for it as it did not do this before you had them attempt this deal. What kind of code reader did they use ? Take it to a dealer prolly was a tranny code(low fluid) that it threw, and can be erased by the dealer, or auto zone .

Cig fuse...

Cool - thanks guys, and that’s what I figured with how low the fluid was that’s what I figured triped the light. But just took the truck for a drive and the light is off now so im guessing Im good.

As others have said it could be the cig fuse or they don't have a newer can-bus based scan tool and just can't connect.

Found the blown fuse... haven’t took it back to see if they can read any codes, but will the code still be in there even if its been off now for a while?

the code will clear after 40 successful passed tests. as far as CAN communications, the 06 model was the first year for this. All other scan tools should work pre-06