I've read through a few threads - not claiming all - trying to pin down some things with this app. I'll be honest, much of the info on the cvtz250 web site is greek to me. Perhaps others have the same problem. This is intended to be the "clearing house" for any such questions, hopefull answered in layman's terms. I'll go first.

In the bottom right corner, highlighted in red, is DTC: CVT. I'm guessing this means DeTeration Counter: DTC. The fact that it's highlighted in red, when everything else is green for OK, I'm wondering what this means.

Thanks.

DTC stands for Diagnostic Trouble Code and the red box means you have one or more stored in your TCM. it may be minor or may be very serious. Go to the home screen and perform Read CVT Codes and Read Engine Codes to see what's going on.

Thanks. Got the code P17F0. I'm not going to ask what this code means; I'm going to ask where can I look it up? For future reference.

That's a "death code", it means the judder-monitor software in the TCM has detected your belt slipping seriously. I'd say 90% of the time it means the belt and/or pulleys are already damaged, but the fact that there are no other codes means the damage may still be minor. The only thing you can try is getting most of the old fluid out of it (3 or 4 quick changes so the fluid is at least 3/4 fresh), but if the belt is badly damaged it won't help.

PS - Nissan doesn't exactly advertise the judder codes, and they won't turn on the engine light. So you'll find precious little official documentation about them. There's a second one that's less serious, P17F1. Neither one is erasable without reprogramming the TCM.

POOP, POOP, POOP, AND FUDGE!
I just bought this in early September with <40K miles and had the fluid changed immediately. It now has almost 40K. What would cause this with so few miles?
Why oh why did I not get the extended warrantee!!! I'll tell you why, because I've never needed one.

Sounds like a leadfoot owned it and did no maintenance. I know I've already briefed you on some CVT do's and don'ts. So a couple of suggestions. First, the 6-cyl CVT's will tolerate a lot more abuse than the 4-cyl's, so with no other codes and mileage that low, there really is a good chance any damage is minor. Get the old fluid out as fast as possible and we'll all cross our fingers.

Second, the MIL doesn't light from judder codes and as you now know, you need special equipment or a very good scanner to read it. I always advise people buying a CVT vehicle to get the tranny scanned with a good shop scanner before they buy, and that's the biggest reason. However, in this case, with only 40K on the clock, it also means the warranty company won't ask many questions and doesn't need to know. Get one now.

PS again - If it's available in your area, all the service writers in our dealership say Route 66 is the best EW as far as coverage, responsiveness and honest service.

Describe "3 or 4 quick changes." Does that mean every 10, 100, or 1,000 miles?

PS: I contacted Route 66.

I'd say give it 200 or so to let the new fluid thoroughly mix (there's always some old stuff trapped centrifugally in the rim of the Torque Converter, and that will take some time to mix in). To keep it simple, just do D&F's with matching amounts on the initial ones, then use the leveling plug on the last pass to make sure it's where it should be.

Speedometer reads 70, CVTz50 read 66. Which is more accurate? Model year 2016.

The speedo on ABS-equipped Nissans gets data from two places, the VSS in the transmission and the ABS wheel speed. The cluster and ECM will both throw DTC's if they differ by more than 5%, although I'm not sure which one the cluster would use if they differ by less than that. In this case what's indicated is more (about 6%), and since you don't have codes, I tend to think the problem is that the speedo needle position is off a bit. Nissan clusters usually over-indicate by about 1~1.5 mph at highway speed, but if the needle is mechanically off a trifle it could read more or less. I've seen it occasionally from the factory. Here's the easiest way to correlate everything: Fire up a GPS app so you can get a known-accurate speed, and compare that with CVTz50 and the speedo reading. Cruise control on a flat road is a good way to avoid too much attention-splitting. You'll probably find CVTz50 matches the GPS more closely than the needle. If so, you know it's an indication problem and you can estimate how much. To find out if it's a mis-located needle or an issue with the cluster drive circuit, take a comparison at two different speeds, say 40 and 80, and see what the difference-of-difference is. If the needle is mis-located then the error will be linear, about the same at both speeds. If it's cluster calibration, the error will be a percentage, about half at 40 what it is at 80. The latter isn't fixable but the former is, those needles just pop off if you remove the cluster faceplate. Drive with the faceplate off at a known GPS speed and pop the needle back on at the correct speed position.

I noticed at lower speeds is the % difference was less. I just used the 70/66 example because that was most of what I was driving today. I'll give the GPS thig a try. That is, if it's available on google maps on my phone. I'm not very techno savvy. As in minimal.

Do a quick search for "GPS speedometer app" and you'll get lots of hits. The one I use is simply called "Speedometer" from an outfit called Cool Niks, but there are a zillion others.

Nah. The last thing I need is another screen to look at while driving. I was just curious about the variation. Not to be disrespectful, but you never did comment on which is more accurate, cvtz50 or speedometer?

It's most likely the speedo is off. Like I said, if the VSS (which CVTz50 is reading) and ABS disagree, you get codes. Since you don't have a lit MIL, the likelihood is it's a display issue.

VStar650CL wrote: ↑

Wed Mar 09, 2022 5:59 pm

PS - Nissan doesn't exactly advertise the judder codes, and they won't turn on the engine light. So you'll find precious little official documentation about them. There's a second one that's less serious, P17F1. Neither one is erasable without reprogramming the TCM.

Hi again Vstar. Our 2017 Quest just came up with P17F1. Picked it up on CVTz50. Tranny has fresh fluid and was not hot, although it's been hovering in the upper 90's here in NW Oregon for the past few days.

It sounds like this is not a catastrophic code (CVT Judder)? Does it mean the VB has to be replaced for sure? How difficult is a VB replacement?

Yah, F1 is basically "minor slippage detected" and almost always means a VB and not a whole tranny, especially if it's caught early. While experimenting because of a different thread, I discovered recently that the vehicles with "squashed-in" engine boxes seem to run much hotter radiator outlet temperatures under load than vehicles with more stretched configurations. In light of that, I'm changing my advice to people with Quests, R52 Pathies, Rogues, and NV200's -- don't install an H-Valve, use an open-loop cooler and select one that's at least a size larger than what a normal A/T would call for.

VStar650CL wrote: ↑

Fri Jul 29, 2022 5:24 pm

Yah, F1 is basically "minor slippage detected" and almost always means a VB and not a whole tranny, especially if it's caught early. While experimenting because of a different thread, I discovered recently that the vehicles with "squashed-in" engine boxes seem to run much hotter radiator outlet temperatures under load than vehicles with more stretched configurations. In light of that, I'm changing my advice to people with Quests, R52 Pathies, Rogues, and NV200's -- don't install an H-Valve, use an open-loop cooler and select one that's at least a size larger than what a normal A/T would call for.

Got it. How hard is it to replace the Valve Body? I found the VB for this vehicle (by VIN) on NPD for $277 which isn't bad. Does the TCM have to be reprogrammed at the dealer after replacement? Would you have to tow it to the dealer? As always, I appreciate your expertise Vstar.

I'll have to look it up for a '17, but I'm fairly sure it's an RE0F10J and those all use a CD for the IP Chars (or a download file, either way obtained from Nissan PCC according to the tranny serial number). You also need the Consult to load them, because the TCM needs special clear-and-read instructions over the CANbus. So it's pretty much a dealer-only thing. The VB's will usually work okay without loading the IP's, but may be very clunky. I'd say it's fine to nurse it to the dealership as long as it isn't a long haul, but watch the temperature. If it starts to wig out or heat up, pull over and get it towed.

Oh, and the VB's aren't hard to replace, the FSM is pretty specific and the '16 FSM here should be identical. I'll double-check that for you tomorrow at the shop.

Your tranny is a regular 10J, so the R&R instructions for the '16 should apply with no differences. You should get a CD with the new IP Chars along with the VB.

VStar650CL wrote: ↑

Sat Jul 30, 2022 9:40 am

Your tranny is a regular 10J, so the R&R instructions for the '16 should apply with no differences. You should get a CD with the new IP Chars along with the VB.

Thanks for checking VStar. Is the "CD with the new IP Chars" for reprogramming the TCM? Is this something I could do through the OBD2 port of is it dealer only? I don't have Nissan Consult or any OBD2 utility other that the CVTz50 app.

Yah, the data is so the TCM knows the electrical vs mechanical curves for each individual solenoid, i.e., X amount of current opens the orifice by Y amount. That programming is pretty much going to be dealer-only, although you may find trans shops that can also do it. There are so many CVT's around these days that the tool companies have started to notice. I haven't found any function in CVTz50 to do it, although I haven't updated the app lately. I have seen people talking about scanners with the capability, but I don't recall what they were. Sorry I can't be more helpful, but with the Consult to use at the shop, aftermarket alternatives aren't something I deal with much.

Vstar - I was debating on whether to do this myself (time-wise) so I called a couple of local Portland OR dealers and got this:
Dealer 1 - VB replace $1600; $160 just to program (if I replace the VB).
Dealer 2 - Said the P17F1 code is mandatory CVT replacement, I said "No, that's for the the F0 code. F1 is VB replace." He said Nissan changed the criteria for the codes but I pressed him and he said he would do the VB replacement for $750 P&L but would not warranty the repair because it would be done on "customer recommendation". (?) I found TSB NTB15-015i that is pretty clear and I couldn't find anything that superseded that TSB.

If I can trust dealer 2 the $750 isn't bad. To do it myself would be just under $500 in parts (including a case of fluid) plus the $160 from dealer 1 to program. It would save me a day in the driveway plus the trip to dealer 1. Can you tell if that TSB is still accurate? I appreciate your help.

I won't be at the shop till tomorrow, but if F1 has become an "automatic replacement" code then it will be news to our whole staff and not just me. Dealer #2 may be doing that because some small number of F1's turn out to fail belt inspection and perhaps they've been burned by telling people, "Oh, it's just a VB." In your case it's been caught early and almost certainly is just a VB, but you're not the typical customer. The $750 is basically ~3 hours labor, which isn't great unless they're doing a belt inspection while it's out. My inclination is to tell you to DIY it and rent a borescope for the day from AutoZone or O'Reillys to do the inspection yourself. Then you can show the pics to whatever dealer does the repro and they'll be, like, "Uh-oh, this Harry actually knows something." You'll get a proper job that way.

Now that I've gotten over the HOT CVT, I've started looking at other things.

Clutch Lockup I looked it up on the cvtz50 site, and this is what it says"
Clutch Lockup – torque converter lockup current; and color indicator showing up when torque converter is in locked up state (corresponding Consult-II parameter: ISOLT1)

Can someone translate that into layman's terms? Is it a good thing or a bad thing?

Besides, I didn't think an automatic transmission has a clutch. There is no third petal.

Actually, conventional A/T's have lots of clutches, and also bands which are basically a cylindrically-shaped clutch. No A/T could shift without the help of clutches and bands. CVT's don't have any of that because they use a belt drive. Of the two clutches they do have, only one is a traditional "wet plate" clutch. That's the Forward/Reverse clutch, and because it only works when shifting in and out of gear, it can last a million miles. The Lockup Clutch is a different animal. It's actually part of the Torque Converter and not the tranny, although it's controlled by hydraulic flow from a valve in the trans. It serves to "lock" the Torque Converter turbine and impeller together so the TC can no longer slip, and it only locks up when the car is cruising above a certain speed in order to improve fuel economy. When the car is stopped the TC of course must slip or the engine would stall, and it also needs to be unlocked to allow slippage when accelerating, climbing hills, or at very low speeds. When the TC lock malfunctions the symptoms are always one of two things, either excessive RPM on the highway if it fails to lock, or constant stalling or no-starts if it isn't unlocking properly.

Here's a pretty good animation of how a TC works:
https://www.youtube.com/watch?v=z5G2zQ_3xTc

TC's for A/T's and CVT's serve the same basic functions, so there are no real differences. Nissan TC's are pretty stout. In general we see few TC failures, including the lockup clutches.

Thank you, thank you, thank you, Mr. VStar650CL. I learned something new and useful today.