P0731 code — how to fix error fast

The code P0731 is one of the most frequent issues with the transmission you can diagnose in a car with an automatic transmission. If that’s what happened to you, the most important thing is to get to the bottom of the P0731 code meaning before the consequences of the code truly hurt your car’s transmission.

To prevent this, we can only advise you to do one thing – get familiar with all the possible reasons behind the code, as well as the main ways of diagnosing and fixing it. Don’t worry though since you won’t be alone on that path as our team will give you all the essential information needed to remove the code.

Why you can trust REREV’s OBD2 code advice: Our automotive expert researchers with experienced mechanics undertakes a thorough research methodology to deliver precise insights on OBD codes. Find out more about OBD2 codes research process..

What does the P0731 code mean?

The code P0731 is a diagnostic trouble code that indicates an issue with the automatic transmission control system. Specifically, it indicates that the transmission is not shifting into the first gear properly. This can cause a range of problems, including reduced fuel efficiency, poor acceleration, and even damage to the transmission.

However, the main symptom that will show up is a distinct difficulty in shifting the gearbox into the first gear. This leads to two other issues – you’ll either struggle to get the tires rolling, or the shifter will try to override the first gear and start from the second which could cause gear slippage. Because of that, it’s essential that we move on with the most important question – what could have caused this code?

What causes the P0731 code?

The code P0731 can be caused by internal transmission problems or electrical issues that may affect your car’s transmission control module (TCM). Still, it’s important to know about all of the possible underlying issues and these are some of the most common ones:

Low transmission fluid

Low transmission fluid can cause the transmission to slip or not shift correctly, resulting in the P0731 code. This is one of the main reasons behind the slipping transmission and if there’s not enough fluid or if it gets contaminated, you’ll have a hard time getting the gearbox into the first gear properly.

Faulty shift solenoid

A faulty shift solenoid can cause the transmission to shift incorrectly, which can trigger the P0731 code. Some cars have a factory-built solenoid that is more prone to damage than others, and it can simply wear off over time, therefore leading to the inability to shift into the starting gear.

Malfunctioning transmission control module (TCM)

A malfunctioning TCM can cause the transmission to shift erratically, resulting in the P0731 code. While this is not the most common situation to see, a faulty TCM can also trigger the code by sending incorrect information to the control module and it may get recognized as a faulty first gear RPM input sensor, therefore leading to the problem with the code.

Damaged clutch plates or bands

Damaged clutch plates or bands can cause the transmission to slip or not shift correctly, leading to the P0731 code.

Symptoms that may be present with the P0731 code include harsh shifting, poor acceleration, and reduced fuel efficiency.

Which car models does the P0731 code affect the most?

The P0731 code can appear in various car models, but it tends to affect certain vehicles more than others. Some of the car models that are most commonly affected by the P0731 code include the following:

• Nissan 350Z: Many owners have reported experiencing the P0731 code, which can be caused by a faulty transmission control module or a worn clutch pack.
• Ford Fusion: Owners of the 2006-2009 Ford Fusion have reported issues with the transmission slipping out of gear, which can trigger the P0731 code.
• Acura TL: The Acura TL experienced similar issues as the Nissan 350Z, especially with sporty versions with a V6 engine.

How to diagnose the P0731 code

Since the code can also be diagnosed as a communication error between the engine’s control module and the transmission module of your car, the easiest way to diagnose it is with an OBD2 scanner. While you can get one yourself to diagnose the code without having to wait for a mechanic, there are some other ways in which you can achieve the same result:

Check the transmission fluid level and contamination

Low or dirty transmission fluid can cause a variety of transmission issues, including the P0731 code. Check your car’s transmission fluid level and condition to ensure that it’s at the proper level and free of debris.

Check the transmission control module

A damaged or worn transmission can also cause the P0731 code to appear. Inspect the transmission carefully for any signs of damage or wear, such as leaks, cracks, or worn gears

Check the transmission shift solenoid

The shift solenoids are responsible for controlling the movement of fluid through the transmission to engage different gears. A faulty shift solenoid can cause the P0731 code to appear. A qualified mechanic can test the shift solenoids to determine if they’re functioning properly.

Check for wiring or electrical problems

In some cases, the P0731 code can be caused by wiring or electrical issues in the transmission system. Check for any loose or damaged wires, corroded connectors, or other issues that could be affecting the transmission’s operation.

How to fix the P0731 code

There are several ways of fixing the code P0731 depending on the underlying issue that caused it to occur in the first place. So, we suggest you make use of one of the following options listed by our team after the diagnosis part is done:

Top-up transmission fluid

Sometimes the solution to the problem with the P0731 code can be easily resolved by simply adding more transmission fluid. In these situations, it’s enough to simply check the fluid level and add it up until it reaches the manufacturer’s recommended specifications to let the transmission work properly.

Repair or replace the TCM

The transmission control module (TCM) is responsible for controlling the operation of the transmission. A faulty TCM can cause the P0731 code to appear. In some cases, the TCM can be repaired, but in other cases, it may need to be replaced.

Fix a faulty shifter solenoid

The shift solenoids are responsible for controlling the movement of fluid through the transmission to engage different gears. A faulty shift solenoid can cause the P0731 code to appear. If a shift solenoid is identified as the problem, it will need to be replaced.

Fix the wiring problem

If any loose or damaged wires, corroded connectors, or other issues are identified, they will need to be repaired.

How to prevent the P0731 code

Preventing the P0731 code involves taking proper care of your vehicle’s transmission. This includes taking care of your car’s transmission system to make sure it operates properly, so here’s what you can do to make it right from the get-go:

• Make use of regular maintenance routines as recommended by the manufacturer
• Check the transmission fluid level in recommended intervals
• Don’t jump through the gears too harshly in the manual mode
• Try to avoid sudden acceleration when possible

By following these steps, you’ll never have to worry about your car starting from the second gear or ending up with a damaged first gear RPM input sensor to make it struggle to spin the wheels.

Our take

Understanding the P0731 code is critical for drivers who want to maintain their vehicle’s transmission and avoid costly repairs. By following the steps outlined in this article, you can diagnose, fix, and prevent the P0731 code and keep your vehicle running smoothly for years to come.

We hope you’ll use the information from t his guide to make it right from the start and make sure this code doesn’t appear again.