P0720 code

[Dwoods215]

Hello everyone,
I have a 2016 Q70L 3.7 AWD, and while driving, my car would not shift out of first gear. I immediately pulled over and had the car towed back home so I could scan it for trouble codes. I retrieved one code, P0720, and another code, P0500. After doing some research, I found that many people recommend replacing the valve assembly unit, while others suggest changing the speed sensor. To be on the safe side, I've decided to replace both.

I checked the price of the valve assembly at the dealership, and of course, it’s quite expensive. Are there any other places I should consider for purchasing this part before resorting to the dealership? I looked on eBay, but most of the sellers seem questionable. I'm willing to do the work myself; I just need some guidance on where to find this part.

[VStar650CL]

OE Nissan Valve Bodies these days come blank, so even if you do the work, you'll need to nurse or tow it to a dealer to have it programmed. You're right to be suspicious of China-cheap clones, they often come with the wrong software and sometimes can't even be reflashed with a correct program. You could swap the TCM to the new VB, but that will be futile if the problem is in the TCM.

That said, P0720 with P0500 points directly to a dead Output Speed sensor. Replacing the VB is probably unwise and unnecessary.

[Dwoods215]

So i did buy the the VB from the dealership because I had no other choice LOL. I took it to a transmission shop that is well known in my area and they confirmed it was the VB and not the speed sensor. I'm back on the road after being down for three weeks. Oh and that VB was $1,700 from the dealer

[VStar650CL]

That's kind of weird, but I think this may be a case of screwed up documentation on Infiniti's part. The exploded drawings in the FSM show the OSS being separate from the VB and located on the outside of the transmission, but the wiring diagrams show it being integral with the VB. Which one is correct, I dunno. I don't have a Q70 handy to look at. However, given that a VB fixed you up, I'll have to assume the EWD is right and the FSM is wrong. I sent an "errata notice" about it to Engineering, we'll see if they correct anything.