I have a 2012 Infiniti G37x sedan with about 150,000 miles on it. I have some simples mods (straight pipe, pop bang tune, cold air intakes) and have been dealing with transmission issues. My old transmission started seeming like it was slipping when accelerating onto the highway and would enter into a limp mode and popped a check engine light. I brought it to the dealership and they said I needed a new transmission. So 3,000$ later I now have a used transmission from a crashed car with about 50k miles on it. Not even a month into driving with this transmission I’m cruising down the highway at about 70 mph (this is my first long highway trip) I go to slowly speed up to about 85 to pass a car when all of a sudden my RPMs drop gas pedal goes dead and I can’t speed up. My car enters a limp mode kind of thing. I have to floor the car to even move and at that point it’s revving up 6-7k RPMs while barely accelerating. The only way to “reset” this is to turn my car off and back on. And even then it’ll happen again 30 minutes later. Wanted to post on here to get any thought before I take it to Infiniti where they tell me I need another new transmission. Also I have been driving very carefully since I got this new transmission. I now have a check engine light and when scanned it gives me a P1734 Code and a P0729 code. Wondering if this is an issue with the transmission, computer, or tune. Infiniti will likely not take any responsibility and blame it on the transmission since I don’t have warranty on it. Let me know any thoughts.

 

I got my used transmission from an Infiniti dealer and it came with a warranty. Take it back.

 

so my transmission has the P0729 and has three codes of the P1734 i was driving on the highway and on the way home it would stay in same gear even when i wouldnt press the gas and it would do a hard down shift whenever i pressed the brakes so im at a stop sign and whenever i pressed the gas it wouldnt go and i was stuck there so i turned my car off and on and once i pass 2000rpm it will lose which gear im in so i would have to turn it off and turn it back on and keep it under 20mph but the minute i hit the 2000rpm it acts like it loses which gear i don’t hear not grinding noise or anything but i was told it was my neutral safety switch but it turns on so i know it’s not that does anyone know what i should do i don’t want to buy a brand new transmission and it just be my tcm,or transmission solenoids im thinking about taking the transmission oil pan off and checking if any metal shavings or if the oil is milky or dirty but i just want to see if anyone has this problem and what did yall do to fix it

 

Any updates?

 

Curious. What does a new-used trannie cost when going through the dealer? I just put one in my son's Ranger and it was close to 3K through an independent. The old trannie had 193K on it, the new-used one has 90K and works well. I'm guessing Ford would have charged 5Kish for the same.

How many miles on your new-used?

 

$2,700. 90,000 miles. They got it from the junkyard. Came with a year/12,000 mile warranty. It shifted better than my old transmission ever did, lol. For a "new" one they were talking $10,000.

 

That's a great price. Came with a warranty of some type? I think mine came with a 90 day warranty provided by the salvage yard we purchased from out in NC. I've replaced just about everything on that truck, so selling it isn't an option anymore so I use it as my spare car.

 

Yes. The 1 year/12,000 mile warranty was through that Infiniti dealer. The $2,700 was my price, parts and labor. They told me it would be $3,300, but when I got the bill it was only $2,700.