Error P0746 by car Nissan Murano - This is one of the most common and critical malfunctions in the operation of an automatic transmission. Code indicates faulty pressure control solenoid valve A (Shift Solenoid A Performance/Stuck Off), which often results in an inability to shift gears or loss of traction at high speeds. Crossover owners often encounter this problem on runs over 100,000 km, when the hydraulic system's life begins to deplete.
Ignoring a fault signal can lead to catastrophic consequences for the transmission. When the electronic control unit (ECU) detects a pressure deviation from the set parameters, it goes into emergency mode, blocking gear shifting. As a result, the car loses its dynamics, and in some cases simply stops moving. Timely diagnosis of the valve body is the only way to avoid a complete replacement of the gearbox.
In this article, we will analyze in detail the mechanical and electronic reasons for the appearance of the code, describe the diagnostic technique and consider repair options, from simple replacement of the solenoid to a complete overhaul of the hydraulic unit. Understanding the essence of the process will help you make the right decision when visiting a service center or when troubleshooting problems yourself.
The essence of error P0746 and the operation of solenoid A
To understand the nature of the failure, you need to understand the principle of operation of the automatic transmission. Nissan Murano. The pressure control system in the valve body uses a series of solenoid valves (solenoids) that dose the flow of transmission fluid to engage certain clutches. Salty valve A is responsible for controlling line pressure that activates certain clutches and brake bands to change gears.
The electronic control unit constantly monitors the position of this valve and the actual pressure in the system, comparing them with ideal data maps. If the valve is stuck in the closed or open position, or if its solenoid coil has a resistance that is outside the permissible limits, the system records an error P0746. This means that the solenoid cannot execute the ECU command and the pressure in the desired line is not achieved.
As a result of this imbalance, the torque converter cannot effectively transmit torque, and the internal elements of the box begin to work with increased wear. It is important to note that the problem may be not only in the electromagnet itself, but also in the hydraulic channels, which over time become clogged with friction wear products.
Main symptoms of malfunction
Manifestations of the error P0746 on Nissan Murano usually begin with slight jerking when changing gears, which over time develops into serious failures. The driver may notice that the car does not upshift when accelerating, constantly being in a low gear and picking up high engine speeds.
The key sign is the inclusion of "Limp Home Mode" - an emergency mode of operation of the transmission. In this mode, the transmission is locked in one gear (usually second or third) to prevent further damage. In this case, the engine may work normally, but the dynamics of the car drops sharply, overtaking becomes impossible, and driving on the highway turns into a test.
Additional symptoms include:
- 💡 The Check Engine indicator lights up on the dashboard and flashes during critical failures;
- 💡 Sharp jerks and impacts when trying to change gears or when switching D-R modes;
- 💡 Increased noise of the torque converter and whistling due to slipping of the couplings;
- 💡 Delay when starting to move from a stop due to insufficient oil pressure in the system.
Causes of failure in the hydraulic system
Reasons for the appearance of the code P0746 can be divided into two main categories: mechanical and electrical. The most common mechanical cause is wear of the solenoid itself or contamination of the valve body. Over time, microparticles of metal and friction material form in the transmission fluid, which enter the thin channels of the valve body, causing the valve to stick.
The electrical part of the problem often lies in an open or short circuit in the solenoid winding, as well as damage to the wiring harness. In the Russian climate, temperature changes and aggressive reagents can accelerate the oxidation process of the connector contacts leading to the transmission. Also, do not rule out problems with the ECU itself, although this happens less often.
List of probable causes:
- 🔧 Sticking of the plunger of solenoid A due to contamination of the hydraulic channels;
- ⚡ Failure of the electrical winding of the control solenoid;
- 🛢️ Low level or degradation of CVT/ATF transmission fluid;
- 🔌 Damage to the wiring or connector connecting to the hydraulic unit.
- up to 80,000 km
- 80,000 - 120,000 km
- more than 120,000 km
- The error appeared after repair
Diagnostics and testing of components
The first step when you find an error is P0746 is computer diagnostics using a professional scanner. It is necessary to read not only the error code, but also see the parameters in real time: solenoid position, line pressure and fluid temperature. This will help differentiate between a mechanical jammed part and an electrical failure.
After reading the codes, it is necessary to conduct a visual inspection of the wiring harness and connector going to the transmission. If the contacts are oxidized or the wiring is frayed, this may cause a false alarm. If there is no external damage, you should check the solenoid resistance with a multimeter, checking the obtained values with the manufacturer's technical standards.
If the electrical part is in order, the next step is to remove and disassemble the valve body. This is a labor-intensive procedure that requires cleanliness and precision. The valve body must be thoroughly washed with a special liquid and blown with compressed air to ensure that the valve is not jammed. The wear of the solenoid guide bushings is also checked.
☑️ Diagnostic checklist
Before starting any work to remove the valve body, be sure to drain the old oil and prepare a container to collect liquids to prevent contamination of the environment and the garage floor.
Repair and restoration options
The solution to the problem depends on the extent of damage to the components. If the reason lies solely in the electrics, it is enough to replace the solenoid or restore the integrity of the wiring. However, most often mechanical cleaning or replacement of the valve itself is required. It is important to understand that simply replacing the solenoid without cleaning the valve body may not have a long-term effect, since dirt will remain in the channels.
In serious cases, when the wear of the valve body is critical, it requires a complete replacement or professional repair with the installation of repair kits (remuters). This includes replacing all solenoids, gaskets and restoring channel geometry. For cars Nissan Murano with a variator or classic automatic transmission, there are special repair kits that allow you to return the unit to factory specifications.
The following table shows approximate prices for various types of work (prices may vary depending on region and service):
| Type of work | Description | Approximate cost (RUB) |
|---|---|---|
| Computer diagnostics | Reading errors and analyzing parameters | 1 500 - 3 000 |
| Solenoid replacement | Removing the pan, replacing 1-2 solenoids, changing the oil | 8 000 - 12 000 |
| Valve block repair | Complete cleaning, replacement of all solenoids and gaskets | 25 000 - 40 000 |
| Replacing the valve body assembly | Installing a new or refurbished node | 50 000 - 80 000+ |
⚠️ Attention: Never try to “drive” the solenoid through the valve body without dismantling it. This can cause dirt particles to come loose from the walls and clog the finer channels, making the situation worse and leading to complete failure of the box.
Prevention and extension of transmission life
To avoid the error reappearing P0746, it is necessary to follow the transmission maintenance regulations. For Nissan Murano It is critical to change the transmission fluid regularly. Many manufacturers claim a “maintenance-free” gearbox, but in practice this means the need for a complete oil change every 60,000 km.
The use of original fluid or high-quality analogues approved by the manufacturer is the key to long-term hydraulic operation. Cheap oils often have insufficient lubricating properties and are prone to rapid oxidation, which leads to the formation of sludge. You should also avoid aggressive driving and overheating of the transmission during long trips with a full load.
Regular monitoring of the oil level and its condition (color, smell) will allow you to notice the onset of problems in time. If the oil turns dark or has a burning smell, this is a signal that urgent diagnostics are needed. Ignoring these signs could cost you the cost of replacing your entire transmission.
Regular oil changes and valve body cleaning are the most effective methods for preventing solenoid errors and extending the service life of the automatic transmission.
FAQ: Frequently asked questions
Is it possible to drive with P0746?
Driving with such an error is highly not recommended. The car will go into emergency mode, which will limit speed and dynamics, and can also lead to overheating and complete failure of the transmission. It is best to call a tow truck and deliver the car to a service center.
How much does it cost to replace a solenoid?
The cost of the solenoid itself varies from 3,000 to 8,000 rubles, depending on the manufacturer (original or analogue). The replacement work, along with changing the oil and filters, will cost an additional 5,000 - 10,000 rubles.
Do I need to change the oil when replacing the solenoid?
Yes, when removing the pan to access the valve body, you must drain the old oil. This is an ideal time to change the fluid and filter to prevent wear debris from getting into the new solenoid.
Could the error appear due to bad oil?
Yes, the use of low-quality or used fluid is one of the main reasons for contamination of the valve body and sticking of solenoids.
What to do if the error returns after repair?
If error P0746 appears again after replacing the solenoid, this may indicate that the cause lies not in the valve itself, but in clogged valve body passages or wear in the mechanical parts of the transmission. In this case, it is necessary to completely clean the valve body and check the condition of the clutches.