Help - 2014 Q50 P0720 Error Transmission not shifting beyond third

In 2014, the G37 Sedan became Infiniti Q50. G37 Coupe and Convertible became Infiniti Q60 under Infiniti's new naming structure - Here's the place to discuss the Q50 and Q60!
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Joined: Fri Jul 17, 2015 11:47 pm
Car: 2007 Infiniti G35 sport

Help - 2014 Q50 P0720 Error Transmission not shifting beyond third

Postby StanleyNii » Sat Jun 01, 2019 3:29 pm

Hello Forum Members. I will be grateful for some assistance on issues with my Car
I have a 2014 infiniti Q50 Sport with 46K miles and has been running smoothly and fine since is bought it used.
Two weeks ago I was driving when i all of a sudden the transmission stopped changing from first gear after i moved from a stop light then the realized also that the check engine light came on. The paddle shifters also stopped working which means it was also impossible to change manually. I then parked the car for about an hour and tried again this time the was driving and shifting smoothly as if there was nothing wrong and i was able to shift with the paddle shifters but wont go beyong 4th gear with the paddles and 5th gear automatically and intermittently the car will slow down as if almost stopping then it will start jerking with the rev counter needle rapidly moving up and down.
I managed to get it to a shop about 10 miles away with the car still going through the sequence i have mentioned about. The car was scanned and two codes came up one was for the ABS sensor which was cleared and the other was P0720 Output speed sensor which cleared but kept coming back when we go for test drive. The car drives and shifts smoothly and accelerates very well but never shifts beyond 4th gear. The paddle shifter have stopped working. I ordered the speed sensor from RockAuto. Took about 2 weeks for me to get it here in Ghana. The mechanic fixed it today and called me. He said that the initial test run went well but subsequently the car drives well but never shifts beyond 3rd gear. He is suggesting a few things.Either the new sensor I bought is defective, the problem could be more than just the speed sensor and maybe the clutches or the valvebody could be fautly or It may be that I have to get a new gearbox.
Anyone here has an idea what this whole drama could be about Kindly Help me.

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Joined: Sun Oct 21, 2018 4:34 pm
Car: 1974 1/2 260z

Re: Help - 2014 Q50 P0720 Error Transmission not shifting beyond third

Postby Z'd_up74RB » Sun Jun 30, 2019 3:31 am

I had the same issue with my 2014 3.7 NA and it ended up being the Sun Gear they end up replacing transmission luckily it was still under warranty only difference was mine would shift up to about 5th or it would not downshift and when I hit the brakes it would act like it was under boost or something and lunge forward

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