Whats up, Mike here. My G35 has 212,000 miles. The trans is acting up. It is taking off in like 3rd or 4th gear? And if i recycle my key it will go away. Then come back. Wierd. I also have no 5th gear overdrive. If i manually shift it it seems like it shifts okay, but still no 5th gear. The rpms will just sky rocket while shifting to 5th manually. I have a nice diagnostic computer and the codes come up as follows: P1721, P0720, P1764, P1759. Any idea? I always baby my car and there all mostly highway miles. Thanks

If recycling the the key will fix some of it then it could have something to do with the TCM (transmission control module). Otherwise, at 212k miles, it sounds like you may need it rebuilt. For the codes I would go through the FSM:

http://www.nicoclub.com/archives/infini ... nuals.html

ec.pdf is the one which will go over the codes.

Okay. Gotcha. That would blow if it will need a rebuild. I may just swap a used one in for all that. Thanks

That would be the cheapest and probably the route I would take as well.

We have found that nearly always P1757 and P1759 (and limp mode as a result) are signs that there is an electrical issue in the valve body. We always inspect EXternal wiring, but it seems that it invariably is INternal to the valve body. Even small amounts of moisture seem to make these valve bodies act up.Thankfully the transmission going into 'limp' mode generally prevents folks from destroying their transmission internals if we see the vehicle promptly.
As part of replacing the valve body we flush the transmission of course.
Don't resign yourself to needing a rebuild when you merely have some codes - We are about 7 to 1 in being able to get folks back on the road with the valve body and a full flush.


Kurt