Codes: P1778, P0746 and P0868

Tiny
SAI_BOLLINENI
  • MEMBER
  • 2011 NISSAN ALTIMA
  • 3.5L
  • V6
  • AUTOMATIC
  • 42,253 MILES
Hi all,

My car has a CVT XTRONIC transmission. A quick summary of my question: my car is diagnosed with these error codes;P0746, P1778 and P0868. Do I need to replace the transmission? Or a transmission specialist would be able to fix the issues? If yes, how to approach for fixing the issues?

Scenario that made me to scan the car for issues.
I recently purchased the car listed above for Christmas. I noticed that after driving for more than thirty to forty minutes in side the city, there was little delay in the acceleration when I depress the accelerator. I checked with a mechanic and he said it is okay and nothing to worry. As it is my first car, I believed him.

couple of weeks back, while driving to another city and at speeds of around one hundred mph, I slowed down the car to make a quick stop. Put the car in 'P', did not turnoff the engine, and put the car back into 'D' to drive again. However, the car was not moving forward! I turned off the car and after an hour started it and this time, the car moved. However, after couple of minutes, I noticed that the power is very less from the car now and the car is not able to climb elevations!

I immediately took to Nissan and they scan the car and told me that I have to go for a new transmission, which costs more than the amount I paid for the car. :(
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Wednesday, March 15th, 2017 AT 9:56 AM

12 Replies

Tiny
HMAC300
  • EXPERT
This is a CVT transmission which are fairly new on market so cost will be higher to fix them. Find a transmission shop that works on them as a lot of guys are not in tune with them yet. Manufacturers are slow to teach outside mechanics about them. The two codes are listed in picture for causes, but 178 is the step motor which means it works okay electrically, but mechanically there is something wrong. It is kind of hard to believe that Nissan would charge more than what you paid for the car unless the person selling it knew of a problem and dumped. There are always junk yards if you do not want to have it rebuilt, but check with a transmission shop first.
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Wednesday, March 15th, 2017 AT 11:51 AM
Tiny
SAI_BOLLINENI
  • MEMBER
Hi HMAC300, thanks for responding.

Can we change the stepper motor in a transmission? Does it require the whole transmission to be opened? From the CVT layout diagram, it looks like the solenoid, stepper motor and TCM are all connected with each other. Is there a chance that an issue in one of those components might have made all three to throw the error codes?

Also, can you explain more on "it works okay electrically, but mechanically there is something wrong"? Please. Do you mean that the component needs to be changed or the error code is due to an issue in another component like solenoids or fluid pressure etc?

Many thanks in advance.
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Wednesday, March 15th, 2017 AT 1:48 PM
Tiny
SAI_BOLLINENI
  • MEMBER
And also, I checked the transmission fluid level after five to seven minutes of starting the car and it is a little above the second bent from bottom of the stick. Is that okay? I can see 'hot' written on the stick above it and the fluid is just below it. If I flush the transmission fluid and change the oil filters, will it help me resolve the error codes?
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Wednesday, March 15th, 2017 AT 2:40 PM
Tiny
HMAC300
  • EXPERT
I really do not think flushing transmission will help at all. What I meant with the one code is that the stepper motor is reading electrically everything is okay it is a mechanical problem inside the transmission so when the dealer told you it needs another transmission they were correct replacing the solenoid and or stepper motor will do absolutely no good. The stepper motor is effected by line pressure so you may have had an oil pump failure as the other two codes relate to low oil pressure so it will not allow the stepper motor to change the gears or make the pulleys move to change them. But everything points to a low oil pressure causing the problem. You transmission fluid level is okay. So changing motor will not help at all and yes it needs to be opened up to replace it. The only other thing I could tell you is to have an independent transmission shop take a peek at it. They may find something different or tell you how much it is to fix it at a cheaper price. But from what I have seen there is a mechanical problem inside the transmission that is needing repair.
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Wednesday, March 15th, 2017 AT 3:29 PM
Tiny
SAI_BOLLINENI
  • MEMBER
Hi HMAC300, hope you are doing great.

I recently had my stepper motor changed and scanned the car for codes. It now shows only P0868 code. I have been driving the car for a week now and the other two codes haven't come up.

I am still working on fixing this error code.

I doesn't feel the car is powerful while trying to accelerate quickly although it has 270hp. Not sure it is due to CVT type transmission or because of this error code - P0868.

As always, very much appreciate your time and help.
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Thursday, March 30th, 2017 AT 5:20 PM
Tiny
HMAC300
  • EXPERT
P0868 is low line pressure and should be looked at by a trans guy as it can be a few things like an oil pump or other things, sensor etc. That is why you feel sluggish, no power you can destroy things pretty easily with low line pressure if you keep driving it.
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Friday, March 31st, 2017 AT 6:41 AM
Tiny
LUCHOAE
  • MEMBER
Hello Sai how are you? My name is Luis and I just checked the problem you had with your Nissan. I am having the same problem as you!The same three codes and also the same acceleration problem. Please please please let me know how did it went with you changing the stepmotor? Thanks Sai!
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Sunday, August 20th, 2017 AT 7:08 PM
Tiny
SAI_BOLLINENI
  • MEMBER
Hi Luchoae,

I am really sorry to hear that you too are having same problems as mine.

I really loved the car, but in the end I sold it for half of the price I bought it for to an agency.

Though I changed the stepper motor, the codes came back after couple of weeks. The main problem seems to be line pressure and my mechanic told me it can be a simple problem to a complex one where he will be required to open the transmission and check.

He was not confident in giving me any guarantee for his work and his price was very high.

So, I decided to sell the car.

If you are living in U.S, getting the transmission fixed or rebuilt should not be a problem. I am living in Mexico and I don't speak much Spanish.

Let me know if you have any questions.
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Wednesday, August 23rd, 2017 AT 11:07 AM
Tiny
KEN
  • ADMIN
Great addition to this thread! Please feel free to help out whenever you are on the site :)

Cheers, Ken
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Thursday, August 24th, 2017 AT 11:16 AM
Tiny
LUCHOAE
  • MEMBER
Hi Sai first of all thank you for taking the time to answer. I was about to buy an stepper motor. I am sorry to hear you had to sell your car, that sucks. Actually I live in Guatemala so warranty is not an option.

Sai just a couple of questions. Did you ever measured your transmission pressure with a test gauge? I was planning on getting a 1000psi gauge, but I wanted to ask you if it made any difference in case you test that before.

And also, did your mechanic checked the solenoids? Or cleaned the line pressure lines in case there was something clogging the solenoid valves? And lastly, did you had to buy a new gasket after opening the oil pan?

Thanks a lot Sai, its a shame you had to sold it, but I really appreciate you are still helping me.
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Friday, August 25th, 2017 AT 10:18 AM
Tiny
SAI_BOLLINENI
  • MEMBER
Hi LUCHOAE,

Yes, my mechanic checked the solenoids. As per him, one solenoid needs to be changed along with stepper motor, which he changed.

From my experience, I can suggest you following -

1. Test the solenoid and stepper motor for their function.
2. Ask a reputed mechanic/agency to check line pressure tests on transmission. Accumulated dirt to damage in the internal lines. It can be anything.

I didn't get my transmission tested for line pressure as the mechanics were charging huge prices for their tests without any guarantee to their work.

If it turns out that the lines inside the transmission are indeed damaged, then its going to be more expensive for transmission rebuilt(close to 30,000 to 50,000 pesos here with only 3 to 6 months warranty) :(

also, one transmission specialist told me that the issue can be with damaged steel belt in the CVT transmission. Which will be too difficult to find and too expensive, at least in the place where I live.

If your transmission has huge number of kilometers, then it can be any of the above listed problems. Only a thorough inspection will help you to find and fix the problem once and for all. Else, you will be investing more time and money with no proper fix on your transmission and with mechanics.

Nissan service manual on transmission has listed out some elaborate steps to identify the issue with low pressure. Make sure your mechanic follows those steps.

I really hope that it is a simple fix for your problem.

Let me know how it went with your car.

Mine was 2011 Altima 3.5 SR.
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Friday, August 25th, 2017 AT 12:18 PM
Tiny
LUCHOAE
  • MEMBER
Hello Sai! Sorry for taking so long on replying. Thank you for your answers they help me a lo with guidance.

Well exactly thats pretty much what we want to do, my dad used to be a Mechanic so we have the programs to follow the proper steps. The first step its supposed to be to test the transmission pressure line with this gauge. Nobody had it so it took me a couple of days to make our own. I have it already and tomorrow we will pressure test the transmission.

After doing that in case that is not the problem. We will take it to a mechanic specialized in AT to check the valve body, solenoids and step motor.

If our pressure tests and the mechanics tests tells us that the problem is inside the transmission, then we are going to change transmission.

In Guatemala luckily is not that expensive. Yes 30k to 50k pesos is way more than here. Here to rebuild the transmission is like 18k to 20k pesos.

My car is a 2010 Nissan Cube 1.8 with a RE0F08B CVT. And with 51,000miles which is not that much.

Sai, did you changed the solenoid as well or just the step motor? Also, did you use new gaskets to reassemble the valve body?

Thanks a lot Sai!

If you ever need help with your car let me know, I owe you, we have some softwares with a lot of data that might help you.
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Monday, August 28th, 2017 AT 6:35 PM

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