P0840 Nissan Code - Transmission Fluid Pressure Sensor 'A'
Quick Answer
The P0840 code for Nissan vehicles indicates a problem with the Transmission Fluid Pressure Sensor 'A'. Common causes include Faulty transmission fluid pressure sensor, Low transmission fluid level, Clogged transmission filter. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0840 Nissan indicates Transmission Fluid Pressure Sensor 'A'.
- Common causes
- Common causes include Faulty transmission fluid pressure sensor, Low transmission fluid level, Clogged transmission filter.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
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Code P0840 Nissan Description
The P0840 code for Nissan vehicles indicates a problem with the Transmission Fluid Pressure Sensor 'A'. This sensor is responsible for monitoring the fluid pressure within the transmission system. If the sensor detects an abnormal pressure level, it will trigger this diagnostic trouble code (DTC). The transmission fluid pressure sensor plays a crucial role in ensuring smooth gear shifts and overall transmission performance. When this sensor malfunctions, it can lead to various transmission issues and potentially cause long-term damage to the transmission system if not addressed promptly.
Common Causes of P0840 Nissan
- Faulty transmission fluid pressure sensor
- Low transmission fluid level
- Clogged transmission filter
- Wiring or connector issues
- Transmission control module (TCM) failure
Symptoms of P0840 Nissan
- Harsh or delayed shifting between gears
- Transmission slipping or jerking
- Transmission overheating
- Illuminated Check Engine Light
- Transmission not engaging properly
How to Fix P0840 Nissan
- Begin by checking the transmission fluid level and condition. Top up or replace the fluid if necessary.
- Inspect the wiring and connectors associated with the transmission fluid pressure sensor for any damage or corrosion.
- Test the transmission fluid pressure sensor using a multimeter to determine if it is functioning correctly.
- Replace the transmission fluid pressure sensor if it is found to be faulty.
- Clear the error codes and perform a test drive to ensure the issue has been resolved.
Cost to Fix P0840 Nissan
The typical cost to repair a P0840 code related to the Transmission Fluid Pressure Sensor 'A' in a Nissan vehicle can range from $150 to $400. This estimate includes the cost of the sensor itself, labor charges, and any additional parts or fluids that may be required. However, actual repair costs can vary depending on the specific diagnosis time and labor rates at different auto repair shops. It is advisable to obtain quotes from multiple shops to compare prices before proceeding with the repair.
Tech Notes for P0840 Nissan
2007-2008 Nissan Altima
2007-2008 Nissan Rogue
2007-2008 Nissan Sentra
The bulletin suggests replacing the transmission valve body.
2007-2008 Nissan Altima, Rogue, Sentra Factory Service Bulletin OBDII Code P0840
2007 Nissan Maxima
2007 Nissan Maxima Factory Service Bulletin OBDII Code P0840
For Nissan vehicles with CVT transmission, Nissan has extended the CVT warranty from 5 years/60,000 to 10 years/120,000 miles
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Frequently Asked Questions about P0840 Nissan Code
1. What are the common symptoms of OBDII code P0840 in a Nissan related to the Transmission Fluid Pressure Sensor 'A'?
- Common symptoms include harsh shifting, transmission slipping, and illuminated warning lights on the dashboard.
2. What are the typical causes of OBDII code P0840 in a Nissan?
- The code P0840 typically indicates a malfunction in the Transmission Fluid Pressure Sensor 'A', which can be caused by sensor failure, wiring issues, or a faulty transmission control module.
3. How can I diagnose OBDII code P0840 in my Nissan?
- Diagnosing code P0840 involves using a scan tool to read the code, checking the wiring and connections to the sensor, and testing the sensor's functionality using a multimeter.
4. Can I continue driving my Nissan with OBDII code P0840 present?
- It is not recommended to drive your vehicle with code P0840 present, as it can lead to further damage to the transmission and potentially result in costly repairs.
5. How can I repair OBDII code P0840 in my Nissan?
- Repairing code P0840 involves replacing the Transmission Fluid Pressure Sensor 'A', addressing any wiring issues, and clearing the code using a scan tool.
6. Are there any DIY tips for fixing OBDII code P0840 in my Nissan?
- While some aspects of diagnosing and repairing code P0840 can be done by DIY enthusiasts, it is recommended to seek professional help for accurate diagnosis and proper repair.
7. How much does it typically cost to fix OBDII code P0840 in a Nissan?
- The cost of fixing code P0840 can vary depending on the extent of the issue, but it usually involves sensor replacement and can range from $200 to $500 at a repair shop.
8. Is it possible for OBDII code P0840 to reoccur after repair?
- If the root cause of the code P0840 is not properly addressed during the repair, there is a possibility that the code may reoccur. It is essential to ensure a thorough diagnosis and repair process.
9. Can a faulty Transmission Fluid Pressure Sensor cause other transmission problems in a Nissan?
- Yes, a faulty Transmission Fluid Pressure Sensor 'A' can cause various transmission issues such as erratic shifting, transmission slipping, and even transmission failure if left unresolved.
10. How long does it take to fix OBDII code P0840 in a Nissan at a repair shop?
- The repair time for code P0840 can vary depending on the shop's workload and the availability of parts, but it typically takes a few hours to complete the sensor replacement and clear the code.
Discuss the causes and fixes for P0840 Nissan OBDII Code
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09 maxima, high engine revolution, very little speed until after a few seconds then it levels out. If I try to pass anyone, the engine just revs, no traction.
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There is definitely a problem with the transmission. You should check with you local dealer, the transmission of your Maxima may still be cover under warranty.
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I got the same code on my 07 Nissan Sentra p0840 trans fluid pressure sensor a and sometimes I brake the car shuts off but that's the only code that's there how do I fix the issue? Plz
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Start by checking the transmission fluid level and condition. There is also a factory service bulletin for your Sentra (see Tech Notes above). The bulletin suggest replacing the transmission valve body to fix the problem.
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EXELENTE INFORMACION; me llegó a mi taller un sentra 2008 con el código P0845, cambié De posición los sensores, y me generó el código P0840
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I get the same code on my 2015 Altima what should i do.. Please help
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Same I suggested above. Start by checking the transmission fluid level and condition, change fluid if necessary and clear the code. If the code comes back, then you may have to replace the transmission valve body.
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I mean no disrespect, I am a machanic but dont have access to proper equipment never needed to use these forums for help but here i am in need of help. How accurate is the code in relations to my nissan i get mixed anwsers when browsing the web
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The information above is the generic Nissan description for the P0840 code, but I just checked the USA Nissan Factory Service Manual, and the 2015 Nissan Altima doesn't use the P0840 code. Please double check the code.
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I recommend start by checking the transmission fluid level and condition. If the fluid is OK, then you should remove the transmission fluid and check for excessive debris on the pan. If no debris is found, then you may have to replace the transmission valve body.
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I got code p0840, when car heat up it's jurk at the time of acceleration, and sometime look like car drive Heavy. Please advise
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Let me check if I can get more more information, what model and year is your Nissan?
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I apologize for the question, but what model is your Nissan? Altima, Maxima, etc? Almost every model have a different engine and transmission.
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More than likely the problem is the Transmission Fluid Pressure Sensor, which is part of the transmission valve body, inside the transmission.
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Thanks for your reply, Car jerk when it's warm up & cold or in cold weather don't jerk, we have to replace the Value body or only TCM ? Please advise
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Hello,
I've got a Nissan Sentra 2008 with 107,000 miles and recently got a P0840 code.
The car is driving well the only issue being that, engine light is ON and it feels under-powered during initial pickup (seems like starting in 2nd gear).
I don't think Nissan will honor the CVT warranty as it's past 10 years. But if they do, would Nissan cover just the parts or labor as well? And can you guesstimate the fix cost?
Also can the error code be suppressed as I'm not facing any significant issue and just need to clear emission test?
Thanks in advance and appreciate the details you have already put up. -
If is cover under warranty they will cover parts and labor.
Replacing the transmission assembly with a new transmission can cost you around $3500.
You could either go to a transmission shop and have them rebuild the transmission, that could cost you around $2000, or get an used transmission for around $1000.Also can the error code be suppressed as I'm not facing any significant issue and just need to clear emission test?
Have you try clearing the code?
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Damn, transmission can be expensive. I did try clearing the code but it was back next day.
As it's a fairly old car I didn't want to invest much in it.
I guess I will have to get it checked at a transmission shop.
Thanks for your quick revert, appreciate it. -
Will the Transmission code P0840 for my 2008 Nissan Sentra Ls clear up with The Sea Foam Cleaner Product bought at the Auto Parts?
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The P0840 code on your 2008 Nissan Sentra refers to a fault with the Transmission Fluid Pressure Sensor "A". This sensor monitors the hydraulic pressure inside the transmission and helps the transmission control module (TCM) manage gear shifting.
Will Sea Foam Cleaner Fix It?
Unfortunately, Sea Foam or similar fuel/transmission cleaners are unlikely to fix a P0840 code. Here's why:
What P0840 Usually Means:
- Faulty Pressure Sensor – The most common cause. The sensor may be giving incorrect readings or failing altogether.
- Wiring or Connector Issue – Corrosion, loose connection, or damaged wiring to the sensor.
- Internal Transmission Problem – Such as dirty fluid or failing valve body components.
- Low or Dirty Transmission Fluid – This can affect pressure readings, but usually won't be solved just by adding cleaner.
What You Should Do:
Check Transmission Fluid Level & Condition – Make sure it’s full and not dirty or burnt. If it’s dark or smells bad, consider a fluid change with the correct CVT fluid.
Inspect Wiring and Connectors – Look for damage or corrosion at the pressure sensor.
Scan with a Proper Tool – A scanner that can read transmission data can confirm if the pressure sensor is giving abnormal readings.
If the code persists, the sensor itself may need to be replaced. It's often part of the valve body, which can be more involved.Summary:
Sea Foam may help with carbon deposits in fuel or light sludge in the engine, but it won’t fix an electrical or mechanical sensor issue inside the transmission. It’s better to diagnose the sensor and fluid condition directly.
Let us know what you find, and we can guide you further!
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