Error P0746 on Nissan Murano Z51: Torque converter and valve body

Error P0746 in the car Nissan Murano Z51 is one of the most common and critical failures encountered by owners of crossovers with a Jatco JF011E continuously variable transmission (CVT). This diagnostic code indicates that the torque converter lockup control solenoid (TCC Solenoid) valve is not operating properly or is stuck in the position. For many drivers, the appearance of this error becomes a turning point that requires immediate intervention from a specialist, since ignoring the problem can lead to complete failure of the gearbox.

Transmission control system Nissan Murano Z51 constantly monitors the rotation speed of the variator input and output shafts. If the computer detects that the torque converter does not lock into the intended driving modes, or does so with a delay, it records an error P0746 and often turns on emergency operation. In this state, the car loses its dynamics, engine speed increases, and fuel efficiency drops sharply, which makes further operation of the vehicle not only uncomfortable, but also dangerous.

There can be several reasons for this code, but the most common is a mechanical or electrical malfunction of the lock control solenoid located on the valve body. Sometimes the problem lies in the wear of the torque converter itself, where the locking friction linings wear out faster than expected, without providing a reliable, rigid connection between the engine and the variator.

Owners Nissan Murano Z51 They often encounter this problem after reaching a mileage of 100-120 thousand kilometers, if the oil in the variator has not been changed regularly. Dirty oil causes deposits to form on the valves, preventing them from moving freely and operating accurately. Critical value It also depends on the quality of the transmission fluid used, since non-original analogues can quickly lose their properties and cause corrosion or jamming of elements.

Often a mistake P0746 accompanied by other trouble codes such as P0745 (line pressure) or P0842 (sensor pressure). This indicates that the problem is systemic in nature and affects not only one valve, but the entire hydraulic system of the variator. In such cases, simply replacing the solenoid may not be enough to completely eliminate the problem.

Symptoms and behavior of the car with error P0746

The first sign of a problem with the torque converter locking up is Nissan Murano Z51 Usually there is a jerk or jolt when switching to a high gear (relatively speaking, when accelerating to 60-80 km/h). At this point, you may feel that the engine is “sagging” a little, and then suddenly picking up speed. This occurs because the system is trying to lock up the torque converter to improve efficiency, but is unable to do so due to a faulty valve.

The second characteristic symptom is an increase in the temperature of the variator. Since the torque converter does not lock up, it continues to operate in slip mode, which generates excess heat. If the transmission temperature light on your dashboard comes on, it means the system is already in critical condition. Don't ignore this signal, since overheating of the oil leads to destruction of the friction clutches and belt drive.

• 🚗 Jerks and jolts when accelerating at speeds above 50 km/h.
• 🌡️ Increase in oil temperature in the variator even during quiet driving.
• 📉 A noticeable decrease in acceleration dynamics and an increase in fuel consumption.
• 🔔 The Check Engine indicator appears on the dashboard.
• 🛑 Enabling emergency mode (Limp Home Mode) with gear limitation.

In some cases, the car may begin to behave unpredictably: twitch when stopping or, conversely, not shift into higher gears. This is due to the fact that the control unit TCM tries to compensate for the error by changing the pressure in the hydraulic system, which leads to unstable operation of the entire transmission.

⚠️ Attention: If you continue to actively use the car when error P0746 appears, there is a high probability of complete destruction of the torque converter. Metal shavings from worn clutches can clog the valve body, resulting in the need for costly repairs to the entire gearbox.

The main reasons for the appearance of a fault code

Diagnosis of the cause of the error P0746 on Nissan Murano Z51 requires an integrated approach. The most likely cause is failure of the solenoid valve (solenoid) for controlling the torque converter lock-up. This element is responsible for opening and closing the oil channels that supply pressure to the locking piston. Over time, the solenoid winding may burn out, and the valve itself may jam due to contamination.

The second most common cause is wear of the torque converter. The friction linings on the locking disk wear off, and the disk no longer presses tightly against the body. As a result, the computer sees the difference in rotation speeds and records an error. Sometimes the problem occurs due to a faulty speed sensor on the input or output shaft, which transmits incorrect data to the control unit.

Wiring problems cannot be ruled out. Vibrations from the engine and transmission can cause chafing of the wires going to the solenoid or oxidation of the contacts in the connectors. Even slight contact with water or dirt in the connector area can cause the sensor to trigger falsely and record an error.

• 💥 Short circuit or break in the winding of the torque converter lock-up solenoid.
• ⚙️ Mechanical wear of the locking disc inside the torque converter.
• 🧼 Contamination of the hydraulic unit with oil wear products and lack of filtration.
• 🔌 Damage to wiring or oxidation of contacts in automatic transmission connectors.

Sometimes an error occurs after changing the oil in the variator if a fluid with unsuitable characteristics was used. CVT oil Nissan CVT Fluid NS-2 or NS-3 has a specific viscosity, and replacing it with an analogue may disrupt the operation of the hydraulics. It is also worth checking the oil level: its lack or excess affects the pressure in the system.

Stages of system diagnostics and testing

The first step when you find an error is P0746 is scanning a car with a diagnostic scanner. It is necessary not only to read the code, but also to view the data in real time. Pay attention to the parameter SLT Solenoid Duty Cycle and the difference in rotation speeds of the input and output shafts. If the difference exceeds acceptable limits when attempting to block, the problem is confirmed.

The next step is to check the solenoid resistance. To do this, you need to remove the transmission pan and disconnect the connector from the valve body. Using a multimeter, measure the resistance of the lockout solenoid winding. A normal value is usually in the range of 2 to 5 ohms. If the resistance is infinitely large (open) or zero (short), the solenoid must be replaced.

It is also important to check the mechanical condition of the solenoid. If you have access to it, try gently pressing on the valve core. It should move freely without jamming. If the valve is stuck, you can try to clean it with a special carburetor cleaner, but this is often only a temporary measure. Cleaning hydraulic unit using ultrasound is a more reliable solution.

If the electrical part is working properly, the problem may lie in the torque converter itself. In this case, it will require its removal and troubleshooting on a specialized stand. The specialist will check the tightness of the locking piston and the condition of the friction linings. Signs of wear on the locking disc are often not visible without completely disassembling the torque converter, so a visual inspection of the case may not provide an answer.

⚠️ Attention: Do not try to disassemble the torque converter yourself without special equipment. Violation of the assembly technology will lead to imbalance and vibrations, which will destroy the variator bearings in the shortest possible time.

Methods for repairing and replacing components

Error repair P0746 on Nissan Murano Z51 Most often it starts with replacing the solenoid valve on the valve body. This is a relatively inexpensive procedure if the problem is just the solenoid. However, if the valve body is very dirty, it is recommended to replace the entire unit or have it professionally cleaned and repaired. Installing a new solenoid on a dirty valve body often leads to repeated failure.

If wear has affected the torque converter itself, it will need to be replaced or restored. Restoration (overhaul) includes replacing the friction disc, piston seal and balancing the housing. This is a more economical option compared to purchasing a new original unit, but requires a highly qualified technician.

• 🔧 Replacing the torque converter lockup control solenoid.
• 🧹 Professional cleaning and repair of the variator hydraulic unit.
• 🔄 Restoration or replacement of the torque converter (converter).
• 🛢️ Replacement of transmission fluid and filter with original consumables.

After replacing components, it is necessary to adapt the variator. Without an adaptation procedure, the new solenoid or torque converter may not work correctly, which will lead to new errors. The adaptation includes learning the switching points and pressures via the diagnostic scanner. The process may take from 20 to 40 minutes.

What to do if the error returns after repair?

If P0746 returns after replacing the solenoid, check the wiring for hidden opens. It is also possible that the torque converter has hidden defects that will appear under load. In rare cases, the problem may be in the TCM itself, which requires flashing or replacement.

It is also important to replace the variator filter and drain the old oil. Even if you are only replacing the solenoid, dirt in the pan can get into the new assembly. Use only original fluid Nissan CVT Fluid NS-2 or NS-3 depending on the year of your car. Do not mix different types of liquids.

Repair costs and prevention

Cost of fixing the error P0746 varies greatly depending on the repair method chosen. Replacing the solenoid with flushing the valve body will cost the least, usually the amount is in the range of 15-25 thousand rubles. Restoring the torque converter will cost more, approximately from 30 to 50 thousand rubles, since it requires removing the gearbox and using specialized equipment.

Buying a new original torque converter is the most expensive option, which can exceed 60-80 thousand rubles without taking into account work. Many owners Nissan Murano Z51 choose the restoration option as it provides a balance between price and reliability. The main thing is to choose a proven service that provides a guarantee for the work performed.

Type of work	Approximate cost (RUB)	Complexity
Diagnostics and scanning	1 500 - 3 000	Low
Replacing the solenoid and cleaning the valve body	15 000 - 25 000	Average
Torque converter restoration	30 000 - 50 000	High
Replacing the torque converter (new)	60 000 - 80 000+	High

Preventing the occurrence of errors P0746 consists of regularly changing the oil in the variator. The manufacturer recommends changing the fluid every 60 thousand kilometers, but for our conditions it is better to do this more often - every 40-50 thousand. It is also important to avoid overheating the transmission, especially when driving in traffic or towing a trailer.

Monitor fuel quality and engine performance. Misfires or unstable engine operation create additional vibrations and loads on the transmission, which accelerates wear on the torque converter. Regular maintenance of the entire vehicle is the key to a long life of the variator.

⚠️ Attention: Never delay diagnosis when the first signs of an error appear. The cost of repairs at an early stage is several times lower than restoring a completely destroyed gearbox after ignoring the problem.

FAQ: Frequently asked questions

Is it possible to drive with P0746?

Short-term - yes, but only in economy mode and without loads. However, prolonged driving with this error leads to overheating of the variator and accelerated wear of the torque converter, which may result in a major overhaul.

Can I fix this error myself?

Replacing the solenoid is theoretically a do-it-yourself repair if you have experience working on the car and the necessary equipment. However, without professional diagnostics and subsequent adaptation of the variator, there is a high risk of not finding the true cause and aggravating the situation.

How often do you need to change the oil in the Nissan Murano Z51 CVT?

Officially, the manufacturer indicates an interval of 60,000 km, but for reliability it is recommended to carry out a partial or complete replacement every 40,000 - 50,000 km, using only the original fluid.

What happens if you don't change the solenoid in time?

Over time, dirt and wear caused by a faulty valve will clog the valve body and can damage the torque converter itself. This will lead to the need for complex and expensive repairs to the entire transmission.

Does this error affect the car's warranty?

If the car is under warranty, the occurrence of error P0746 should be corrected by the dealer free of charge, provided that you have undergone routine maintenance from an official dealer and have not violated the operating rules.