When the Check Engine light comes on on the dashboard, car owners Nissan often encounter code P1722. This diagnostic code indicates a problem with the transmission input speed sensor, which is a critical element for the automatic transmission to operate correctly. Without receiving correct data on the rotation speed of the input shaft, the ECU cannot calculate the correct gear shift time, which leads to jerking, slipping, or going into emergency mode.
Ignoring this signal can lead to serious mechanical damage inside the valve body or planetary gears of the box. In modern models such as Nissan X-Trail or Teana, the electronics are so sensitive that even a minor failure in the sensor circuit is instantly detected by the system. Understanding the nature of this error and the ability to carry out initial diagnostics will help save significant money on repairs in specialized service centers.
The essence of the problem and the purpose of the speed sensor
The Input Speed Sensor is responsible for monitoring the speed at which the automatic transmission input shaft rotates. This information is transmitted to the electronic control unit (ECU) in real time. Based on this data, the computer compares the rotation speed of the engine and the output shaft, determining the degree of slippage of the clutches and the need to switch gears.
Code P1722 appears when the ECU receives a signal from the sensor that is beyond acceptable limits or is absent altogether. This may mean either a physical breakdown of the element itself, a break in the wiring, or problems with the mechanical part of the transmission. It is important to understand that in systems Nissan This sensor is often integrated into the torque converter housing or mounted directly on the transmission housing.
Symptoms can range from a slight increase in shift time to complete blocking of movement. In some cases, the car goes into "Limp Home" mode, where driving is only allowed in one or two gears. You won't be able to diagnose the problem without knowing exactly how the system works in your specific model, be it Nissan Qashqai or Murano.
The main causes of code P1722
The range of reasons causing this error is quite wide and requires careful system analysis. Most often, the problem lies in the sensor itself, which over time loses its magnetic force or the electronic part fails. However, you should not immediately blame all sins on him, as the reason may be deeper.
- 🚫 Speed sensor malfunction: The internal winding or magnetic element has degraded, resulting in signal distortion.
- 🚫 Wiring problems: Oxidation of contacts in the connector, chafing of insulation or breakage of wires going to the control unit.
- 🚫 Mechanical damage: Sensor contamination with metal shavings due to wear of transmission gears.
- 🚫 ECU failures: In rare cases, the problem may be with the software or the control unit itself.
Particular attention should be paid to the condition of the transmission fluid. If the oil in the box is overheated or contaminated, this may affect the operation of the sensor, even if it is technically sound. In such situations, changing the oil often does not solve the problem, since the error is already recorded in the controller’s memory.
⚠️ Attention: Do not try to reset the error by simply disconnecting the battery. If the physical cause is not eliminated, the code P1722 will return instantly after the first start of the engine and may cause repeated jerking when driving.
Diagnostics and visual inspection
The first step in troubleshooting is a visual inspection of the sensor installation area. You will need access to the transmission housing. On many models Nissan the sensor is located on the top or side, which allows you to get to it without completely disassembling the unit. Inspect the connector for signs of oxidation, moisture, or mechanical damage to the housing.
Use a multimeter to check the sensor resistance. Standard resistance values typically range from 150 to 250 ohms, but the exact numbers vary depending on the vehicle model. If the readings fall outside these limits or indicate an open circuit, the sensor must be replaced. Don't forget to also check the integrity of the wires coming from the connector to the ECU.
If the electrical part is OK, you need to check the condition of the transmission fluid. Remove the magnet from the box tray (if accessible) and inspect it for metal shavings. A large amount of chips may indicate that the sensor is clogged with metal particles that distort the magnetic field.
- Every maintenance
- Once a year
- Only in case of problems
- Never checked
Step-by-step instructions for replacing the sensor
The process of replacing the input speed sensor requires care and adherence to the sequence of actions. Start by de-energizing the vehicle by disconnecting the negative terminal of the battery. This is necessary to prevent short circuits when working with electrical connectors. Raise the car on a lift or use secure stands.
Locate the sensor location and disconnect the electrical connector. Carefully unscrew the fastening bolt and remove the sensor. When removing, be careful not to damage the O-ring. Clean the seat from dirt and old oil before installing a new part.
- ✅ Preparation of tools: A set of wrenches, a multimeter, a new sensor, a clean rag.
- ✅ Checking a new element: Before installation, make sure that the resistance of the new sensor is correct.
- ✅ Seal installation: Be sure to replace the rubber ring to avoid oil leakage.
- ✅ Connector connection: Make sure the connector clicks into place.
☑️ Check before launch
After installing the new sensor, connect the connector and return the battery terminal to its place. Now you need to reset errors from the ECU memory using a diagnostic scanner. Start the engine and allow it to warm up while observing the real-time data readings.
⚠️ Attention: If after replacing the sensor there is an error P1722 returns, the problem may not be in the element itself, but in the mechanical part of the transmission or in the control unit. In this case, in-depth diagnostics using professional equipment is required.
Checking wiring and connector
Often the cause of the error lies not in the sensor, but in the power or ground circuit. The wires leading to the transmission are subject to vibration and high temperatures, which eventually leads to their destruction. You need to ring each wire from the sensor connector to the ECU connector.
Please refer to the wiring diagram for your specific model. Check for voltage at the power contacts when the ignition is on. If there is no voltage, the problem may be in the fuse or the ECU power relay. Also check the ground circuit for corrosion or poor connection to the body.
Pay special attention to the connector. The contacts inside may oxidize or move apart, which will lead to an intermittent error. Clean the contacts with contact cleaner and, if necessary, bend them to ensure a tight connection.
Before starting electrical work, be sure to insulate all exposed contacts to avoid short circuits when driving the vehicle on rough roads.
Mechanical causes and consequences
If electrical diagnostics do not reveal problems, mechanical causes should be considered. Worn input shaft gears or damage to the ring from which pulses are read can cause a code to appear. P1722. In this case, the sensor is working, but does not receive the correct signal.
Contamination of the transmission fluid with metal shavings is also a common cause. Chips can stick to the sensor's magnet, creating false signals or blocking the sensor's operation. In such cases, it is necessary not only to replace the sensor, but also to flush the valve body and replace the filter.
In rare cases, the problem may be related to the torque converter. If the torque converter lock-up clutch is not working correctly, it may affect the shaft speed, which the ECU interprets as a sensor error. This requires complex diagnostics using pressure gauges and an oscilloscope.
What to do if the chips are in oil?
If you find a lot of metal shavings on the tray magnet, this is a sure sign of serious wear and tear on the box. Simply replacing the sensor will not help - you will need a major overhaul of the automatic transmission or replacement of the complete unit.
Prevention and operating tips
To avoid the error reappearing P1722, it is necessary to follow the transmission maintenance regulations. Regular oil and filter changes are the key to a long life not only of the valve body, but also of the speed sensors. Use only original oils or analogues recommended by the manufacturer.
Avoid overheating the transmission. When towing or driving heavily in traffic, monitor the oil temperature. Overheating leads to degradation of the lubricant and accelerated wear of parts, which ultimately affects the operation of the sensors. Install an additional oil cooler if the vehicle is frequently driven in difficult conditions.
When you notice the first symptoms, such as rough shifting or an illuminated Check Engine light, do not delay diagnosis. Catching the problem early can save you from costly repairs to your entire transmission. Regularly check the condition of the wiring and connectors, especially if the car is operated in conditions of high humidity or dust.
Regularly changing the transmission fluid and checking the condition of the wiring are the most effective ways to prevent error code P1722 and extend the life of the automatic transmission.
Table of error codes and their interpretation
For a more accurate diagnosis, it is useful to know what other codes may accompany P1722. Often it comes with errors related to the output speed sensor or control solenoids. Understanding the relationship between these codes will help you quickly find the root of the problem.
| Error code | Description | Probable Cause |
|---|---|---|
| P1722 | Input speed sensor malfunction | Sensor, wiring, mechanics |
| P1723 | Output speed sensor malfunction | Shaft speed sensor |
| P1711 | ATF temperature sensor malfunction | Oil temperature sensor |
| P1724 | Speed sensor signal does not match | Input/output speed mismatch |
FAQ: Frequently asked questions from owners
Is it possible to drive with error code P1722?
Short-term - yes, but only in emergency mode and with caution. Long-term operation with this error can lead to complete failure of the gearbox due to incorrect shifting.
How much does it cost to replace a speed sensor on a Nissan?
The cost of the sensor itself varies from 1,500 to 5,000 rubles, depending on the model. Replacement work usually costs from 1,500 to 3,000 rubles, if dismantling the pallet is not required.
Do I need to change the oil after replacing the sensor?
If you drained the oil or removed the pan during the change, then yes, it is highly recommended to change the oil and filter. If the sensor was changed without draining, then an oil change is not necessary, but is advisable for prevention.
Why does the error return after a reset?
This means that the physical problem has not been resolved. Either the sensor is faulty, or there is a break in the wiring, or there is a problem in the transmission mechanics. It is necessary to repeat the diagnosis.
Can I replace the sensor myself?
Yes, if you have access to a lift and a minimum set of tools. However, to check the wiring and reset errors, it is still recommended to have a diagnostic scanner.