Code P0021 on Nissan Murano Z50: Complete Diagnosis and Troubleshooting Guide

Error P0021 is one of the most common problems encountered by crossover owners. Nissan Murano first generation (Z50 body). This diagnostic code indicates that the engine management system has detected a discrepancy between the actual position of the exhaust camshafts and the requested position set by the electronic control unit. In particular, we are talking about bank 2, which corresponds to the cylinders located on the right side of the engine compartment (when viewed in the direction of travel), which is typical for V6 engines of the VQ35DE series.

Ignoring this problem can lead to serious consequences for the engine, since the violation of the valve timing affects the efficiency of fuel combustion, power and environmental friendliness of the exhaust. Owners often notice a decrease in acceleration dynamics, unstable idling and the appearance of a characteristic ringing noise during a cold start. Timely diagnosis and elimination of the causes of the error will help to avoid expensive repairs of the cylinder head or replacement of the engine itself.

The essence of the problem and the mechanism of operation of the VCT system

Valve timing control system (CVTCS) on engines VQ35DE is a complex hydraulic mechanism controlled electronically. The engine control unit (ECU) calculates the optimal opening angle of the intake or exhaust valves depending on load and speed. To do this, solenoids are used that supply oil under pressure to phase shifters installed at the ends of the camshafts.

Code P0021 means that the ECU is trying to rotate the exhaust camshaft on the right cylinder head (Bank 2) to a certain position, but the actual rotation angle is not achieved within the specified time. This may be due to mechanical jamming, insufficient oil pressure, or electrical faults in the control circuit. Progressive error causes the engine to go into emergency mode, limiting speed and power.

It is important to understand that the error itself does not always indicate a breakdown of the phase shifter itself. Often the problem lies in the quality of the oil, clogged channels or a faulty solenoid. However, if you ignore the code P0021 over a long period of time, the phase shifter gears may become mechanically damaged, which will require a complete replacement of the unit.

The main causes of code P0021

Diagnosis of a malfunction should begin by eliminating the simplest and cheapest causes before proceeding with disassembling the engine. Most often the problem occurs due to contamination of the oil system or worn components. Below is a list of the most likely culprits:

• 🔧 Low level or poor quality engine oil, leading to a drop in pressure in the CVTCS system.
• 🔧 The phase control solenoid (OCV Valve) is dirty or stuck, which blocks the oil supply to the phase shifter.
• 🔧 Mechanical wear of the timing chain and tensioners, which changes the valve timing on an ongoing basis.
• 🔧 Failure of the phase shifter itself (VCT unit) due to wear of the internal gears or destruction of plastic elements.
• 🔧 Open or short circuit in the wiring to the Bank 2 solenoid.

Particular attention should be paid to the condition of the oil. VQ35DE motors are very sensitive to replacement intervals and lubricant viscosity. If the oil has not been changed for more than 10,000 km or the wrong product has been used, deposits will form inside the engine and clog the thin oil passages in the phase shifter. This leads to the fact that the mechanism simply cannot budge, despite commands from the ECU.

Diagnostic Steps and Circuit Test

Before removing the phase shifter, you need to make sure that the electrical part is in good condition. To do this, you will need a multimeter and access to the solenoid connectors. First check for power at the solenoid connector with the ignition on. If there is no voltage, the problem may be the fuse or the wiring to the relay.

Then measure the solenoid winding resistance. For engines Nissan This generation, the normal resistance value is usually in the range of 7 to 15 ohms at 20°C. If the meter indicates an open circuit (infinite resistance) or a short circuit (0 ohms), the solenoid must be replaced. Also check the integrity of the wires coming from the ECU to the solenoid for chafing or oxidation of the contacts.

⚠️ Attention: When checking electrical circuits, always disconnect the battery before starting work to avoid short circuits and damage to the electronic control unit.

If the electrical is good, the next step is to check the mechanical functionality of the solenoid. It can be removed and blown out with compressed air, checking how the internal plunger moves. It should move freely, without jamming. A dirty solenoid can often be cleaned in an ultrasonic solvent bath, but if it is mechanically worn out, replacement is required.

Mechanical diagnostics and oil condition

The most common cause of error P0021 at mileage over 150,000 km is physical wear of the phase shifter. Inside the mechanism body there are gears that wear out over time, or a plastic stopper that can burst. In this case, the mechanism may jam in one position or have a large backlash. To verify this, you need to remove the solenoid and inspect the oil filter (mesh) on the phase shifter body itself.

If metal shavings or large wear particles are found on the mesh, this is a sure sign that the phase shifter requires replacement. Also pay attention to the condition of the timing chain. Lengthening the chain leads to a phase shift, and although the system tries to compensate for this, with strong stretching, the adjustment limit can be exhausted, which is where the error is recorded. Stretched chain often accompanied by a characteristic metallic clanging sound when starting the engine.

It is very important to check the oil pressure in the system. To do this, you need to connect a pressure gauge to the standard hole for the oil pressure sensor. Low pressure, even with a working oil pump, but clogged channels, will not allow the phase shifter to operate. If the pressure is normal, but the error persists, the problem is localized precisely in the mechanics of the camshaft or its drive.

In some cases, the problem may be hidden in the camshaft position sensor (CMP sensor) itself. Although it usually produces its own specific codes, incorrect data from it can confuse the phase control algorithm. Check the signal from the sensor with an oscilloscope or scanner in real time.

Why shouldn't you drive with error P0021?

Long-term operation with disturbed valve timing leads to overheating of the exhaust gases, increased fuel consumption and accelerated wear of the catalyst. In the worst case, this can cause detonation and damage to the piston group.

Procedure for replacing and adjusting the phase shifter

If diagnostics show a faulty phase shifter (VCT) on Bank 2, it will need to be replaced. The replacement process on the VQ35DE engine is not the easiest, as it requires removing the valve cover and possibly other attachments for access. It is important to maintain cleanliness: dirt that gets inside the block head can cause repeated failure.

When installing a new assembly, be sure to use a new solenoid and phase shifter gasket. Apply fresh engine oil to the O-rings before installation. After installation, it is necessary to fill in fresh oil if it has not been changed recently. This is critical to flushing the system and ensuring new components are lubricated.

After replacing parts, it is necessary to reset the error and carry out the training (adaptation) procedure. In some cases, the ECU remembers wear parameters and cannot immediately switch to working with a new mechanism. This may require a specialized diagnostic scanner capable of performing the "Learning" or "Reset Camshaft Position" function.

Sometimes, even after replacement, the error returns. This may indicate that the problem was not with the phase shifter alone, but with the overall oil pressure or with a solenoid that was replaced but is defective. In such cases, it is recommended to replace both solenoids (intake and exhaust) at once, since they operate in the same environment and have the same mileage.

Prevention and maintenance recommendations

To avoid the P0021 error occurring in the future, you must strictly follow the maintenance schedule. Change the engine oil every 7,000 - 10,000 km, even if the manufacturer claims longer intervals. Using quality oil with the correct viscosity index (usually 5W-30 for Murano in our climate) is critical to the operation of the CVTCS hydraulic system.

Monitor the condition of the fuel system and catalyst. A clogged catalytic converter creates back pressure, which can affect the performance of the exhaust system and, indirectly, the position sensors. It is also recommended to periodically clean the throttle body and idle air valve to keep the engine running smoothly.

If you hear strange noises when starting the engine, especially a metallic clanging sound that lasts 1-2 seconds, don't ignore it. This may be a sign that the phase shifter is slow or the chain tensioner is worn out. Early contact with a specialist will save you significant money on repairs.

Use only original spare parts or high-quality analogues from trusted manufacturers when replacing solenoids and phase shifters. Cheap aftermarket parts often have poor quality seals and cannot withstand high temperatures, leading to a rapid loss of pressure and the reappearance of the error code.

Table of characteristics and typical faults

For clarity, we present a table comparing the parameters of a working system and typical deviations that cause error P0021. This will help you quickly navigate when diagnosing yourself.

Parameter	Normal (Proper)	Deviation (Error P0021)	Probable Cause
Solenoid resistance	7-15 Ohm	Infinity or 0 Ohm	Winding break or short circuit
Oil pressure (idle)	1.5 - 2.0 bar	Below 1.0 bar	Pump wear or clogged channels
Phase advance angle	0-40 degrees (adjustable)	Locked in extreme position	Mechanical jamming VCT
Condition of the oil grid	Clean, no chips	Clogged with dirt or shavings	Engine wear, old oil

Frequently asked questions (FAQ)

In this section we will answer the most frequently asked questions from owners Nissan Murano Z50faced with this problem.

Is it possible to drive with error code P0021?

Technically the engine will start and drive, but this is not recommended. The engine will operate in emergency mode with limited speed and power. Long driving can lead to overheating and damage to the catalyst or the engine itself due to incorrect ignition timing.

Should I change the phase shifter on both heads at once?

If the phase shifter on one head (Bank 2) is worn out, there is a high probability that it is in a similar condition on the other (Bank 1). Replacing both nodes at once will save you time and money in the future, since the work of accessing them is equally labor-intensive.

Will an engine flush help with P0021?

Flushing can only help at the initial stage, when the mechanism simply jams slightly from carbon deposits. If there is already mechanical wear on the gears or destruction of plastic elements inside, flushing will not help and the unit will need to be replaced.

How much does it cost to repair a phase shifter?

The cost varies greatly. The original phase shifter is expensive, but there are high-quality analogues. In service, replacement work takes from 3 to 6 hours, depending on the complexity of access and the need to remove additional units.

Critical: If P0021 is accompanied by a metallic ringing noise at cold start that does not go away after warming up, stop the engine immediately and perform a full inspection of the timing chain and tensioners to avoid a broken chain.

Solving the problem with code P0021 requires a systematic approach. Do not try to simply erase the error with a scanner, as it will return very quickly. Only eliminating the physical cause - be it dirt, electrical or mechanical wear - guarantees the stable operation of your Nissan Murano in the future.