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Discussion Starter · #1 ·
I've been pulling the P0868 code "transmission fluid pressure low" regularly since a couple of months. It always appeared as "history" and the car would work fine, so I didn't think much about it. But though I kept erasing it kept coming back, always as "history".

Since yesterday, the transmission has been jolting. The car works fine when cold and then when cruising in and around town, it jolts a bit like if on a manual transmission, one was depressing and releasing the clutch brutally while keeping the other foot on the gas pedal. Then it starts behaving as if, still on a manual transmission, some gears were damaged and jumping. The trans works fine when stepping strongly on the accelerator.

I noted the Technical Service Bulletin (TSB) NTB05-084A :
1) Hesitation while accelerating from a stop or while driving.
2) The Service Engine Soon (SES) light is not illuminated on your gauge cluster.
3) Code P0868 is stored in the Transmission Control Module (TCM).

I have no hesitation while accelerating from a stop, but for the rest it looks to be a match.
I cleaned the loom connection to the transmission as this is one of the steps recommended. The problem is still there...

I see from some threads that Nissan has been replacing whole transmissions with that code... Ours is out of warranty, and I'm not sure we invest in a new transmission if that's what the issue ends up being.

I am now hesitating to take the car to the dealer to have them diagnose the issue more precisely, or order and replace the valve body.

Any help or recommendation would be welcome.

This is a 2003 model with 150,000 miles on it. Transmission fluid was replaced 15,000 miles ago with the correct Nissan fluid and the level is OK.

Thanks for the help !
 

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P0868 usually comes up when you are moving. So on-board diagnosis is needed to see when it actually happens-during hesitation. But yeah, you can gamble on replacing the entire valve body but its still 50/50 chance it may not work. Its totally up to your financial situation. Dropping 5-6K for a remanufactured tranny is no joke. Even reman tranny from the dealer is iffy at times. At least there is warranty on the unit. But not on labor. You can try changing fluid several times and drive the car that way(hesitating at will) until it stops you completely. It may last for a long time with hesitation. But its not only annoying, could be dangerous in certain traffic situations. Maybe a new/used car is in your future. Good luck.
 

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You could try dropping the oil pan, cleaning it out along with the filter screen attached to the valve body and see if that helps. It could also give you a good idea of how much wear/tear the CVT has depending on how much debris and sludge you find.
 

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Discussion Starter · #4 ·
Thank you for your responses.

From what I have read online and with that code, the dealer will either propose replacing the transmission (most likely) or only the valve body. We won't invest in a new transmission given cost, car's age and mileage. So I took my chances and just ordered a remanufactured valve body and a new filter and gasket for the pan. I will see how it goes.
 

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The P0868 code is a generic OBD-II code that detects a problem with the transmission fluid pressure. Transmission fluid serves to lubricate the transmission, and for vehicles with automatic transmissions, to cool the transmission system as well. When the powertrain control module (PCM) detects that the pressure of the transmission fluid is either too high or too low, the P0868 trouble code will be triggered.
 

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That is the main code that points to the worn flow control valve in the oil pump. The only way to access that is to remove the transmission and split the case.
To see that valve look here. And scroll down to post number #67, it shows what a worn valve looks like it can leak or stick to cause the P0868 and is the number 1 reason to get that code. I don't think a reman valve body will help. But if your planning to rebuild that transmission it maybe a good idea to have it. Also some of the cheap online reman valve body's end up not working very good. So hopefully you got one from a well known outfit.
 

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Discussion Starter · #7 ·
Thanks, chidog. I read that other thread and realized the incredible work you and redline are currently engaged in. Just removing the trans looks to be a PITA. If that valve body replacement doesn't work, I will see what the next step is. My main problem is that I don't spend much time at home due to my job, so it would take me ages to take the transmission out and repair it. I can't leave my wife without a car during all that time. And having it done will cost way more than what the car is worth.

I have a stupid question: If I still have the pressure problem after swapping the valve body, could a slightly thicker oil be a reasonable stopgap measure? If so, what oil/additive should I use?
 

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I have a stupid question: If I still have the pressure problem after swapping the valve body, could a slightly thicker oil be a reasonable stopgap measure? If so, what oil/additive should I use?
If you want to embark on a magical mystery tour of what can be experimentally put into a CVT, check out some of @Cryogenix1's early threads...
 

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Yes the CVT is a different deal as far as adding thicker fluids and such. It would be an experiment for sure. And yes how brilliant of them (JATCO) to make it so the whole transmission needs to come out and split the case to get to the flow control valve. But then even most all normal step transmissions need the same removal to get to the oil pump and valves. It would have been fairly easy for them to make access to that valve by just removing the oil pan and valve body.

My biggest slow down on this project right now is trying to find the transfer gear taper roller bearings, mine where discolored from heat, its just not a very good lubrication system they have for them.
I know they have had bearing distress on the JF011E I think it is, in jeeps bad enough to chew up the rollers and races, so don't think its a good idea to use bearings that likely have been softened by over heating.
 

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Discussion Starter · #10 ·
OK, so I received the “rebuilt” valve body which I just replaced with eight quarts of new Nissan NS-2 fluid.

The good news is that the transmission is not jolting anymore (as if it went in and out of gear rapidly) and it did not throw the P0868 code over the twenty miles that I drove the car. I don't know if it is the valve body or the new oil which fixed the issue. I did not find a lot of sludge, but the magnets were looking like porcupines and there were some shiny shavings in the oil. I took pictures and will post them later.

The not so good news is that the car is now throwing the p1778 code - faulty stepper motor - which it wasn't throwing before. From a standstill the engine is now revving a lot (up to 4000 rpm) to launch the car, then the transmission starts working normally.

So, I'm now thinking of taking the stepper motor out of the old valve body as it wasn’t throwing any codes and fitting it onto the “rebuilt” valve body. I will do that tomorrow morning. In the meantime, if any of you has some insight or recommendations, they will be most welcome.

Thanks a lot in advance.
 

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Before my 2003 AWD blew a head gasket around 301,000 miles, I was getting P1778 and P0868 and experiencing "overtaching" that refers to when the tach is above 3000RPMs and the car is hardly moving. You might find this thread helpful, but it is lengthy. P1778 step motor, bad CVT, low speed/power, over-taching...

Instead of replacing the valve body or step motor, I changed the fluid a few times over three months, and it made a major difference. FYI, despite the overtaching issues starting around August 2019, I was able to put on something like 60,000 miles from then until April 2021. It required a slight relearning of how to drive when the car hasn't been driven for a number of hours and everything is cold. Once warmed up, the car ran beautifully, despite the codes popping up. The attachments show what my internal filter and pan magnets looked like. Just loaded/clogged with metal shavings.

I seem to recall a thread in the Altima forum that mentioned something about having to have the dealer reprogram the TCM once a new valve body is installed. Rather than risk doing more harm by fooling around with the step motor, maybe it would be better to have them do a reprogram of the system to see if that solves the problem. In this case, I believe that's what I, personally, would do, despite not liking dealerships all that much.

Here's my other thread that talks about P0868 and P1778... Rear differential, transfer case, CVT filter/fluid...
 

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Discussion Starter · #12 ·
Thanks, Cryogenix1. I read your thread on P1778 and I experience similar symptoms, though not as bad: the car moves normally at parking speed without having to let it warm up. As the issue wasn't there with the other valve body and the new issue is about a malfunctioning solenoid, I will swap them out and see what happens. If the issue persists then I will see for a reprogramming at the dealership.

BTW: my magnets looked the same as yours. I don't think the pan came off before and the car has 150,000 miles. My filter was looking better than yours.
 

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Did you transplant your old ROM, onto the rebuilt valve body? Very important to do that. If you don't do that then you need to go to the dealer and have them reprogram it for you. And hope they don't mess something up by accident or on purpose.
A valve body would not have helped the transmission I am working on, the flow control valve was bad. The valve body so far is okay, will know better after I vacuum test it.
 

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Using an old ROM on a different valve body that probably isn't precisely to the same tolerances as the previous one, I'd venture a guess that it won't work optimally. I'm guessing the TCM reprogram procedure has the Consult-II monitoring the actions of all the solenoids and components, torque converter speed and fluid flow through the system over a period of time to get accurate data, then that data and those parameters are programmed into the TCM so it knows how to choreograph the process of making all the parts work in perfect harmony. Your old ROM and TCM programming might be thinking solenoid "1A" is providing a line pressure of 1.1111, when the new solenoid is actually providing 1.1112, which might affect how everything works. Now, imagine if other components aren't parametered correctly to align with what the TCM thinks is happening. Here, again, this is my opinion. I'm sure some of the senior members have some actual knowledge about the reprogram process where I'm merely using reasonable speculation.
 
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Discussion Starter · #16 ·
I just replaced the stepper motor with the old one. Things have improved in that the car works fine from a standstill. the engine is still racing up to 3000 rpm if I get to pick up speed at light throttle from 5 to 15 mph, without having come to a standstill. If I stump more frankly on the gas pedal in the same conditions then it works normally, without racing. Once it started racing, easing on the gas pedal back to 1000/1500 rpm and then accelerating again stops the racing.

It is still throwing code P1778, but without the engine light coming on this time.

Not sure of what the issue is now. At least my wife is back on the road, though she will have adapt her driving a bit. I will keep looking for a solution. I will see if I can have the TCM reprogrammed.

Thanks all for the help so far, and please let me know if you have any further ideas.
 

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Hard to say if an update will help. I remember one member mentioned getting an update and help his P0868 issue. But several members did the same but did not help. Again, its a gamble. If you can spare a hundred bucks or so then maybe its worth a try. Try erasing the code or disconnecting your battery for a few minutes. Good luck.
 

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Discussion Starter · #18 ·
Thanks nitely. I did disconnect the battery about 15 minutes and keep erasing the code but the issue comes back. Will keep looking for a solution. At least now the car is kind of useable.
 

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The comment about reprogramming to pressures may partially be correct its difficult to say, not knowing for sure how they do that. And actually it should be a TCM relearn deal as well. Since it uses the pressures and speeds to figure things out. Just remember the main cause for P0868 is the flow control valve problem. Also not so much a problem but could cause pressure errors is the pressure sensors.
They would be easy to check if the data about them was available. I have no trust for any auto fix it place, even one well trusted by a family member, I feel set they the car up for a problem. They couldn't even get the proper side written down that had a bad wheel bearing, didn't know left from right.
 

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Discussion Starter · #20 ·
I also thought there should be some relearn capacity. We will drive the car around a bit and see how it goes.

I do not have the code P0868 anymore. Just the P1778 that I didn't have before replacing the valve body. It looks like these two valve body are having two different issues. I may be able to make a good one out of the two, though I have no idea of what to swap from one onto the other. May be swapping the pressure sensors from the "new" valve body onto the old one and refit the old one on the car?
 
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