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Nissan Sentra P0846: Meaning, Causes and Diagnosis

 

P0846 Nissan Sentra

P0846 is a relatively common fault code. While your Nissan Sentra’s check engine light comes on, P0846 is a trouble code related to the transmission, specifically the transmission fluid pressure sensor circuit.

It is a generic code, so P0846 has the same definition for any vehicle manufactured after 1996. Before doing anything, check your Sentra’s transmission fluid.

Abbreviations used in this article:

  • PCM– The powertrain control module is the main computer module that controls the engine and transmission in a single unit
  • TCM– The Transmission Control Module controls the transmission shifts and is separate from the engine control module. Your Nissan Sentra will have a PCM or a TCM. And, for this article, they are interchangeable.
  • TFPS– Transmission fluid pressure sensor

P0846 Definition: TFPS “B” Range/Performance

P0846 Meaning Nissan Sentra

Here is the definition of P0846 for the Nissan Sentra broken down by its individual parts

Transmission fluid pressure sensor/switch

The TFPS has two main functions:

  1. Convert transmission fluid pressure into a signal that the PCM/TCM can use to control shifting.
  2. Verifies that the PCM/TCM request for a transmission shift has occurred.

Circuit “B” Range/performance

The TFPS converts hydraulic pressure data into a voltage signal that your Sentra’s TCM/PCM can use to control the transmission. P0846 occurs when this signal is outside the normal operating range for this signal.


P0846 Symptoms: Nissan Sentra

These are the most common symptoms associated with P0846:

  • Limping mode– Your Sentra will shift differently and will not have access to all gears.
  • check engine light– There will often be other codes that occur with P0846. They are usually related to voltage and power.
  • Erratic change– Shifts may be smooth (RPM drops slowly during shifting), or they may be too abrupt (RPM drops sharply).

Nissan Sentra P0846 Causes + Diagnosis

P0846 Diagnosis: Nissan Sentra

Diagnosing P0846 on the Nissan Sentra can be challenging due to the location of the TFPS sensor and the wiring associated with it.

1. Check other codes and TSB’s

The first thing you should do is check other diagnostic codes (such as P0841). They can provide valuable clues about what’s happening inside your stream.

TSBs are technical service bulletins. Nissan uses them to solve common and known problems. Check if there are any related to TFPS. You can get them on the NHTSA website, and they can make diagnosing P0846 easier.

2. Inspect TFPS wiring

The next thing you’re going to want to do is inspect the wiring that goes to your Sentra’s TFPS. If it is burned or damaged, you will need to replace/repair it.

After that, clear the trouble codes from your Sentra and see if the P0846 appears again.

Whether or not you can access TFPS will determine whether most people can still diagnose P0846. TFPS can sometimes be accessed from outside the stream. You may have to open the transmission.

Wiring problems are the most common cause of P0846. Take your time and make sure the harness is in good condition.

3. Other causes

  • Defective TFPS sensor
  • Internal transmission problem
  • Low transmission fluid level
  • Defective TCM/PCM

Although a bad TFPS sensor is very likely, make sure the voltage is correct and does not change when you move the harness before replacing it.


Conclusion

Diagnosing P0846 is quite simple. The real problem is getting to the wiring and the TFPS. Good luck repairing your Sentra!

 

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