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Discussion Starter · #1 ·
so I was on the highway the other day and check engine light came on. this p0720 code came up and the car won’t go into manual mode idk what this is. Took the car to auto zone to scan and the code was p0720 but the the guy said it was a transmission issue so please my Infiniti bros tell me that auto zone is wrong and it’s just a sensor
 

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so I was on the highway the other day and check engine light came on. this p0720 code came up and the car won’t go into manual mode idk what this is. Took the car to auto zone to scan and the code was p0720 but the the guy said it was a transmission issue so please my Infiniti bros tell me that auto zone is wrong and it’s just a sensor
Actually, it is a sensor...the output speed sensor inside the transmission.

P0720 - This DTC comes up when there is a discrepancy between what the output speed sensor senses as a vehicle speed and what the wheel speed sensors see. The car will go into fail-safe mode, prohibiting manual shifting and limiting gear shifting to 1st,2nd, and 3rd gears, as you experienced.

Unfortunately, this isn't a simple fix. The transmission assembly(1) has to be separated from the rear extension(10) in order to access the sensor (9).

101515


The ATF has to be drained, the rear engine cover removed, the exhaust pipe removed, the propeller shaft assembly separated, control rod removed, and the ATF pan and gasket removed before you can separate the transmission from the rear extension. Supporting the transmission with a transmission jack, the rear engine mounting member needs to be removed and then the bolts can be removed to release the rear extension from the transmission assembly. Then you can finally access the output speed sensor.

I don't know the level of mechanical knowledge or tools you may have so you may want to consider having a shop do this. This is assuming you don't have a wiring/connector problem which is unlikely. Others here have had that sensor go out so I'd assume it's the sensor over a wiring/connection problem.
 
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When others had the issue did Infiniti fix under warranty?
 

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When others had the issue did Infiniti fix under warranty?
I don't recall specifically whether they were on or off warranty. Should be part of the drivetrain warranty if it hasn't expired.
 

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That's good because that is a ridiculous list of steps to fix that sensor problem.
 

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Discussion Starter · #6 ·
Actually, it is a sensor...the output speed sensor inside the transmission.

P0720 - This DTC comes up when there is a discrepancy between what the output speed sensor senses as a vehicle speed and what the wheel speed sensors see. The car will go into fail-safe mode, prohibiting manual shifting and limiting gear shifting to 1st,2nd, and 3rd gears, as you experienced.

Unfortunately, this isn't a simple fix. The transmission assembly(1) has to be separated from the rear extension(10) in order to access the sensor (9).

View attachment 101515

The ATF has to be drained, the rear engine cover removed, the exhaust pipe removed, the propeller shaft assembly separated, control rod removed, and the ATF pan and gasket removed before you can separate the transmission from the rear extension. Supporting the transmission with a transmission jack, the rear engine mounting member needs to be removed and then the bolts can be removed to release the rear extension from the transmission assembly. Then you can finally access the output speed sensor.

I don't know the level of mechanical knowledge or tools you may have so you may want to consider having a shop do this. This is assuming you don't have a wiring/connector problem which is unlikely. Others here have had that sensor go out so I'd assume it's the sensor over a wiring/connection problem.
Actually, it is a sensor...the output speed sensor inside the transmission.

P0720 - This DTC comes up when there is a discrepancy between what the output speed sensor senses as a vehicle speed and what the wheel speed sensors see. The car will go into fail-safe mode, prohibiting manual shifting and limiting gear shifting to 1st,2nd, and 3rd gears, as you experienced.

Unfortunately, this isn't a simple fix. The transmission assembly(1) has to be separated from the rear extension(10) in order to access the sensor (9).

View attachment 101515

The ATF has to be drained, the rear engine cover removed, the exhaust pipe removed, the propeller shaft assembly separated, control rod removed, and the ATF pan and gasket removed before you can separate the transmission from the rear extension. Supporting the transmission with a transmission jack, the rear engine mounting member needs to be removed and then the bolts can be removed to release the rear extension from the transmission assembly. Then you can finally access the output speed sensor.

I don't know the level of mechanical knowledge or tools you may have so you may want to consider having a shop do this. This is assuming you don't have a wiring/connector problem which is unlikely. Others here have had that sensor go out so I'd assume it's the sensor over a wiring/connection problem.
Actually, it is a sensor...the output speed sensor inside the transmission.

P0720 - This DTC comes up when there is a discrepancy between what the output speed sensor senses as a vehicle speed and what the wheel speed sensors see. The car will go into fail-safe mode, prohibiting manual shifting and limiting gear shifting to 1st,2nd, and 3rd gears, as you experienced.

Unfortunately, this isn't a simple fix. The transmission assembly(1) has to be separated from the rear extension(10) in order to access the sensor (9).

View attachment 101515

The ATF has to be drained, the rear engine cover removed, the exhaust pipe removed, the propeller shaft assembly separated, control rod removed, and the ATF pan and gasket removed before you can separate the transmission from the rear extension. Supporting the transmission with a transmission jack, the rear engine mounting member needs to be removed and then the bolts can be removed to release the rear extension from the transmission assembly. Then you can finally access the output speed sensor.

I don't know the level of mechanical knowledge or tools you may have so you may want to consider having a shop do this. This is assuming you don't have a wiring/connector problem which is unlikely. Others here have had that sensor go out so I'd assume it's the sensor over a wiring/connection problem.





this must had happen to you because that’s what all the videos said about the when I tired to look it up online do you how much would this cost for shop(dealership)or diy for part…
 

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this must had happen to you because that’s what all the videos said about the when I tired to look it up online do you how much would this cost for shop(dealership)or diy for part…
No, fortunately it hasn't happened to me. The sensor runs about $125. You'll need new ATF, gasket for the transmission pan, and liquid gasket for the rear extension also. Labor cost? I'd make a wild guess of $800 to $1000. Call your dealership and ask them what it would cost.
 

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That's good because that is a ridiculous list of steps to fix that sensor problem.
Why do you say that? The sensor is installed into a key area of the transmission to sense what needs to be sensed.

How would it be made any easier to change? Maybe it could be a bit easier, but I would imagine that most of the steps outlined above would still be needed.
 
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Ya OK still its an expensive and involved process to replace a $100 sensor.
 

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Ya OK still its an expensive and involved process to replace a $100 sensor.
I appreciate the perspective, but the cost of the part being replaced isn't relevant to the process, i.e. labor, it takes to replace it.

Another example is a leaking rear subframe differential bushing. Fairly inexpensive part that requires a lot of work to replace. All cars have these kinds of items everywhere on them.
 
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Discussion Starter · #11 ·
No, fortunately it hasn't happened to me. The sensor runs about $125. You'll need new ATF, gasket for the transmission pan, and liquid gasket for the rear extension also. Labor cost? I'd make a wild guess of $800 to $1000. Call your dealership and ask them what it would cost.

Well the dealership said that just the transmission itself is life 5k but if it’s just a sensor why do I need replace the whole transmission
 

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Discussion Starter · #12 ·
Well the dealership said that just the transmission itself is life 5k but if it’s just a sensor why do I need replace the whole transmission

I would think just cause if the simple fact that the it switch to manual would that require to do the whole transmission
 

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Well the dealership said that just the transmission itself is life 5k but if it’s just a sensor why do I need replace the whole transmission
If it's only the output speed sensor, there's no reason to replace the transmission. Something tells me we're not getting the whole story here.
 

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Discussion Starter · #15 ·
If it's only the output speed sensor, there's no reason to replace the transmission. Something tells me we're not getting the whole story here.
What whole story? I was driving on the highway the check engine light came on went to auto zone got a scan p0720 code came up and I just wanna know if I need to replace a sensor or the whole transmission because I’m just now finding out that it doesn’t go into manual mode after doing more research..
 

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What did the dealer say when you asked why they couldn't just replace the sensor and quote that work?
 

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Discussion Starter · #17 ·
What did the dealer say when you asked why they couldn't just replace the sensor and quote that work?
What did the dealer say when you asked why they couldn't just replace the sensor and quote that work?
All that is irrelevant to the situation. I just need information if I need to replace the whole transmission or just a sensor? Do I need to break down the transmission to get to the sensor because it’s in the transmission or do I need to replace the transmission and sensor all together.
 

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Discussion Starter · #18 ·
All that is irrelevant to the situation. I just need information if I need to replace the whole transmission or just a sensor? Do I need to break down the transmission to get to the sensor because it’s in the transmission or do I need to replace the transmission and sensor all together.
Beacuse it don’t go into manual mode because of the sensor or beacuse of the transmission
 

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All that is irrelevant to the situation. I just need information if I need to replace the whole transmission or just a sensor? Do I need to break down the transmission to get to the sensor because it’s in the transmission or do I need to replace the transmission and sensor all together.
I disagree. The dealer may have had information or an explanation on why the transmission should be replaced, which would answer the very question you're asking.
 

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All that is irrelevant to the situation. I just need information if I need to replace the whole transmission or just a sensor? Do I need to break down the transmission to get to the sensor because it’s in the transmission or do I need to replace the transmission and sensor all together.
I already explained that above. Didn't you read my post? Your DTC indicated a bad output speed sensor. I explained how to get to the sensor. If it's just the sensor, there's no reason to replace the transmission unless the service department found other problems besides the sensor and determined the transmission is bad. The fail safes you are experiencing (no manual shift, restricted gear shifts) are triggered by the DTC. If the faulty output speed sensor is replaced, the car will shift normally again.

Sheesh!
 
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