One of the most common problems faced by crossover owners Nissan Murano, especially models with a V6 engine, is the appearance of diagnostic code P0021. This code indicates a malfunction of the variable valve timing (VCT) system on the intake camshaft of cylinder B. When the electronic control module detects that the actual camshaft position is not the same as the programmed one, an indicator on the instrument panel will illuminate Check Engine, and the machine goes into emergency mode.
Ignoring this problem can lead to serious consequences for the power unit. Improper operation of the VTC system will affect power, fuel consumption and idle stability. In some cases, if the oil has not been changed for more than 15,000 km, the hydraulic actuator may jam, which will require expensive repairs or replacement of the camshaft. It is important to understand that the P0021 code itself rarely indicates a breakdown of one specific component; it is only a signal of an imbalance in the operation of the system.
The essence of the problem and the mechanism of operation of the VCT system
To understand the nature of error P0021, it is necessary to consider how the variable valve timing system functions. In engines Nissan VQ series (for example, VQ35DE or VQ35HR) installed on Murano, hydraulic couplings are used on the camshafts. The ECU controls solenoids that open and close the passages to supply engine oil under pressure. This pressure turns the phase shifter, advancing or retarding the opening moment of the valves.
Trouble P0021 means that the system cannot achieve or maintain the required position on the bank 2 intake camshaft. Bank 2 is usually located on the side where there is no exhaust manifold (opposite the first cylinder). If the camshaft position sensor detects a lag, and the ECU sees that the solenoid is already open to the maximum, it issues this code. The problem can be either mechanical or electrical.
Symptoms often do not appear immediately. At first, you may notice only a slight change in the sound of the engine at idle speed. However, as the problem worsens, acceleration failures and increased fuel consumption appear. In critical situations, the car may stall when stopping at a traffic light.
The main causes of code P0021
The list of possible causes for this error is quite wide, and you need to start diagnosing it with the simplest ones. The most common reason is the quality and condition of the engine oil. The VCT hydraulic system is extremely sensitive to lubricant viscosity and purity. If the oil is thick or clogged with wear debris, it cannot quickly and effectively push the phase shifter mechanism.
The second most common culprit is a faulty VCT solenoid (actuator). These solenoid valves become contaminated with metal shavings or carbon deposits over time, causing the valve stem to no longer move freely. A breakdown of the electrical circuit is also possible: oxidation of the contacts in the connector or a break in the wire leading to the solenoid.
More complex and expensive causes include mechanical wear of the VTC itself or stretching of the timing chain. If the chain is stretched, the system will not be able to compensate for this phase change, even with good solenoids and clean oil. It is also worth checking the oil pump, since insufficient pressure in the system will not allow the VTC to operate.
Diagnostics and step-by-step testing of components
Before buying new parts, it is necessary to conduct a thorough diagnosis so as not to waste money. Start with a visual and electrical inspection. Disconnect the connector from the VTC solenoid on the second bank and check for oxidation or damage. Measure the solenoid resistance with a multimeter; for engines Nissan it is usually between 7 and 13 ohms.
If the electrical is ok, move on to checking the mechanical part. Remove the solenoid and inspect its strainer. If it is clogged with dirt, this may cause delayed operation. Try blowing it out with compressed air. Also check whether the solenoid rod itself is jammed by pressing on it with your finger - it should move freely under pressure and return with a spring.
An important step is checking the oil channels. Sometimes the oil pump filter becomes so clogged that the pressure in the system drops below a critical level. In this case, replacing the solenoid will not help, and you will need to flush the engine or replace the oil pump. Don't forget to also check the oil level and condition.
☑️ Checklist for diagnosing error P0021
Table of possible malfunctions and methods for eliminating them
For clarity, we have collected the main causes of error P0021 in the table. This will help you navigate the procedure for diagnosing. Remember that repair costs vary greatly depending on the identified cause.
| Cause of malfunction | Symptoms | Elimination method | Difficulty of repair |
|---|---|---|---|
| Contaminated or old oil | Floating speed, engine noise | Changing the oil and oil filter | Low |
| Faulty VTC solenoid | Code P0021, no response to scanner | Replacing the solenoid with a new original | Average |
| Clogged VTC filter | System response delay | Cleaning the filter or replacing the solenoid | Average |
| Stretched timing chain | Metallic ringing, cold error | Replacing chain, sprockets and tensioners | High |
| VTC phase shifter wear | Strong knocking noise on a cold engine | Replacing the camshaft assembly | Very high |
⚠️ Caution: Never try to clean the VTC solenoid with harsh chemical solvents such as acetone or brake cleaner, as this may damage the rubber seals, causing oil leakage and repeated failure.
- Old oil
- Dirty solenoid
- Stretched chain
- Wiring problems
Solenoid repair and oil change
In most cases, the problem is solved by replacing the VTC solenoid and a good oil change. For engine Nissan Murano with code P0021, it is best to use original spare parts. Cheap alternatives often have less precise valve settings, which can cause the error to return after several thousand kilometers. The solenoid replacement process is relatively simple and does not require removing the engine.
Before installing a new solenoid, be sure to clean the installation area and check for metal shavings on the solenoid magnet. If you see a lot of chips, this is a signal that there is active wear inside the engine, and replacing the solenoid alone will not do. In this case, it is necessary to conduct a complete diagnosis of the internal components of the motor.
After replacing the solenoid and oil, it is necessary to reset the errors with the scanner and carry out the valve timing training procedure. This can be done through the OBDII diagnostic connector using specialized equipment. Without this procedure, the ECU may incorrectly interpret data from the sensors, and the error will return.
When replacing the solenoid, be sure to use a new O-ring. An old ring may lose elasticity and begin to leak oil, causing a drop in pressure in the VCT system.
Mechanical Problems: Chain and Phase Shifter
If replacing the solenoid and oil did not help, and the P0021 code returns, the cause lies deeper. The most unpleasant situation is wear of the VTC mechanism or stretching of the timing chain. On engines VQ35 phase shifters have their resource, and after a certain mileage they begin to “whistle” or knock when cold, and then give errors.
Timing chain stretching is a common problem on runs over 150-200 thousand kilometers. When the chain is stretched, it begins to dangle, and the VTC system cannot keep the phases in the desired range. In this case, replacement of the chain, tensioners and dampers is required. This is a labor-intensive job that requires removal of the attachment and part of the engine.
Sometimes the problem can be in the camshaft itself. Wear of the cams or seats for the phase shifter makes the system impossible to operate. In such cases, replacement of the camshaft assembly is required. This is an expensive procedure and is often carried out only after a thorough check of all other systems.
How to check chain stretch without disassembling the engine?|You can use a scanner to view the parameters in real time. If the "Timing Advance" or "Cam Angle" value consistently deviates from normal even under warm-up and load, this is a sign of chain stretch or VTC wear.-->
Adaptation and error reset procedure
After carrying out any work related to the timing system or replacing the solenoid, it is necessary to perform the adaptation procedure. The ECU must remember the new engine operating parameters. This often requires the use of a professional diagnostic scanner capable of communicating with the engine control unit Nissan.
The procedure usually involves warming up the engine to operating temperature, turning off the ignition, waiting a certain amount of time and then performing a driving cycle in different modes. Some scanners have a "Reset Cam Angle" or "VTC Learning" feature that automatically performs this process.
If you do not have access to professional equipment, you can try the standard reset method by disconnecting the battery terminal, but this does not guarantee successful adaptation. In this case, the error may return after several engine starting cycles, since the system has not undergone the training procedure.
⚠️ Attention
Do not try to reset the error by simply removing the battery terminal if you are not sure of the quality of the repair. This may cause problems with other vehicle systems, such as the power windows or audio system.
Repair costs and prevention tips
The cost of troubleshooting P0021 varies greatly. Replacing the solenoid and oil will be relatively inexpensive, but replacing the timing chain or camshaft will require a significant investment. The estimated cost of replacing the solenoid is about 30-50% of the cost of replacing the timing chain.
To prevent this error from occurring in the future, follow the maintenance schedule. Change the oil at least once every 7-8 thousand kilometers, using only the viscosity recommended by the manufacturer. Also check the condition of the air filter regularly, as a dirty filter can lead to a lean mixture and increased engine wear.
Use high-quality consumables and spare parts. Cheap oil filters may not provide the required pressure, which is critical to the operation of the VTC system. Remember that prevention is always cheaper than repairing serious mechanical damage.
Frequently Asked Questions
Is it possible to drive with error code P0021?
It is possible to drive for short periods, but it is not recommended. The engine will operate in emergency mode, which can lead to increased fuel consumption and reduced power. Long-term use can worsen mechanical damage.
Do both VTC solenoids need to be replaced at once?
If the error is only on one bank (P0021), it is not necessary to change both. However, if the mileage is high, replacing both solenoids may be more beneficial in the long run, since the second one may soon fail.
Why does the error only appear when it is cold?
This may indicate wear on the phase shifter or chain stretch. On cold oil, the viscosity is higher, and the system cannot quickly work out the phases. There may also be a problem with oil pressure when cold.
Which oil is best to use for prevention?
It is recommended to use genuine Nissan oil or quality equivalents with a viscosity of 5W-30 or 5W-40 that meet API SN specifications or higher. Avoid low viscosity oils on older engines.
Could P0021 be a false alarm?
Yes, sometimes an error can be caused by a poor contact in the connector or a temporary drop in voltage in the on-board network. In such cases, the error may disappear by itself after restarting the engine.