Hello Everyone!

New to the forum, but I have these codes that I hope you will be able to help me out with. Ill make the story as short and concise as I can.

At around the 300,000 km mark, my sentra started having tranny issues. From a dead stop, it will rev really high (3-4000 rpm) before slamming into gear. Seems to happen more in extreme temperatures. When Im on the highway the RPM's will surge, especially on hills, when its really windy, or if I have alot of people in the vehicle.

Soon after a DTC code of P1777 came up.

I did some research and apparently this is the end game for the CVT transmission, and you either have to rebuild it or replace it. Some rebuild videos on youtube however have stated that the main issue is a valve in the oil pump of the CVT. If you replace the valve or get a rebuilt oil pump with a new valve, it can solve these issues.

I was thinking if DIY'ing this and giving it a shot. The parts seem to be readily available and cheap. The time it would take me is significant however. Prolly 4-5 days as Ive never done this type of thing.

Has anyone done this and had success? If you have, any advice would be welcome. I dont want to waste my time trying this if the fix doesn't work or isn't relatively long lasting lol.

Here is the video that mentions the oil pump:
https://www.youtube.com/watch?v=0ibNYcT4UkQ

Thanks!

douche_a_roni wrote: ↑

Mon Feb 15, 2021 4:55 pm

At around the 300,000 km mark, my sentra started having tranny issues. From a dead stop, it will rev really high (3-4000 rpm) before slamming into gear. Seems to happen more in extreme temperatures. When Im on the highway the RPM's will surge, especially on hills, when its really windy, or if I have alot of people in the vehicle.

Has it had any fluid changes? If not, at 300K km I guarantee it has bigger problems than the Valve Body. If you've given it at least minimal maintenance (every 60K miles or so, 100K km), that might be a different story.

Fluid change @ 200,000 and 300,000 km. Fluid looked brown in colour each time I changed it.

douche_a_roni wrote: ↑

Mon Feb 15, 2021 11:28 pm

Fluid change @ 200,000 and 300,000 km. Fluid looked brown in colour each time I changed it.

That's good, then if you don't have a lead foot you might get away with a valve body. The early 4-cyl VB's all had a problem with soft materials in the VB causing long-term solenoid failures. Brown fluid is normal for 100K changes, that's a long an interval unless you're a very gentle driver in a cold climate. Your best course is if the local parts store will rent you a borescope, take a look at the belt and pulleys for scoring after you get the VB down. If there's any evidence of metal-to-metal contact then put it back together and return the VB, you'll need a rebuild. If they're clean, go ahead with the VB replacement. Take a look at this bulletin, it's for an Altima but it will give you a good idea of what to look for:

https://www.nissan-techinfo.com/asistgc ... /1UW15.PDF

Since the IP information on the early CVT's is stored in the VB, you'll also need to reinitialize the TCM after replacing the VB. That takes a Nissan Consult or other high-end scanner that can do CVT work support. If you have access to a suitable tool, this bulletin describes the how-to:

http://pdf.textfiles.com/manuals/AUTOMO ... 8-064a.pdf

If not, have a dealer do it. You can see from the bulletin that the procedure isn't complicated, it just requires a capable scanner. The TCM's existing data has to be erased and data from the new VB read-in to replace it.

PS - This TSB has your VB part number and a list of the other NRP parts you'll need:

https://f01.justanswer.com/xsvectOR/31a ... 0d_nt1.pdf