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VCT Solenoid – What are the Signs of a Faulty Solenoid?

VCT Solenoid

A VCT, also known as a variable camshaft timing, is an automobile variable valve timing technology that has been developed by Ford, one of the biggest American Automotive companies in the entire United States and the world. This technology allows for the best engine performance and running at an optimal level. 

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The variable camshaft timing can also reduce emissions, which is good for the environment, and increase fuel efficiency by enhancing the miles per gallon ratio compared to other vehicles that contain just fixed, or stationary, camshafts.

VCT Solenoid Mechanism

A variable camshaft timing uses electronically controlled hydraulic valves, also known as solenoids, that direct pressure oil into the camshaft phaser cavity. A solenoid is a type of electromagnet that generates a controlled magnetic field through a coil that is wound tightly and can be arranged to produce a uniform magnetic field. 


These oil control solenoids bolt directly into the cylinder heads near the front of the engine, directly next to the camshaft-phasers. The powertrain control module, also known as the PCM, transmits a signal to the solenoids to move a valve that determines the level of the flow of oil to the phaser cavity. 


The phaser changes the valve timing by rotating the camshaft, and the PCM adjusts the camshaft timing. If the camshaft timing and the powertrain control module are not working correctly, then you will experience VCT solenoid issues in your vehicle. 


Basically, the VCT solenoids included within the variable camshaft timing mechanism are in charge of rotating the camshaft and operating the power control module, which allows for better control of oil, causing better fuel efficiency and reduced oil waste. 

  • Twin Cam Engine VCT Solenoids

For twin cam or DOHC engines, VCT solenoids are used on either the intake or exhaust camshaft, using variable camshaft timing for improved emissions. Vehicles with VCT also do not require exhaust gas recirculation. Gas recirculation is a technique used in petrol or diesel engines to recirculate the engine’s exhaust gas back to the engine cylinders. 

  • Powertrain Control Module

The powertrain control module controls the camshafts’ timing by using a VCT Solenoid to allow oil pressure to enter the camshaft phaser at a specific level. 


The VCT solenoid is an electronically controlled valve that is determined by the PCM. Depending on this VCT solenoid position, it allows oil pressure to enter the phaser or keep moving to stop camshaft timing. The PCM itself can modulate timing several times per second or per unit of time since the VCT solenoid’s timing is mechanical and hydraulic. 

  • Phaser

The phaser used in this VCT system consists of an outer component attached to the sprocket and a mechanically linked portion by a chain to the inner component. The phaser obtains oil directly from a camshaft center and travels through a block into the phaser.

  • Phaser Pins

The phaser’s two main pins are a stationary locating pin on the inside and a locking pin preventing unintended movement and located inside the phaser unit. Oil pressure is then fed to the pin by the solenoid, releasing the phaser and allowing the VCT solenoid and operation to begin. 

Faulty VCT Solenoid Symptoms

Let’s check out various problems that can occur when a VT solenoid is wearing out or has broken down. These signs can even go as far as to cause engine failure. In order to reduce the potential of these situations from really damaging your car completely, here are a few warning signs that can show a problem with the VCT Solenoid

  • Check Engine Light

Since an engine control unit controls many modern cars available today, almost every single part is monitored by the ECU. The ECU, or the engine control unit, is a type of electronic control module that controls a series of actuators on an internal combustion engine to ensure the best engine performance and high-performance capabilities.  


When one part of your engine is beginning to fail, the engine control unit stores a specific trouble code that can scan the system and know where, why, and how that problem exists. Once the system has produced that code, it will signal to the driver that something is wrong by illuminating a light on your dashboard. The most common light that comes on is the Check Engine LIght when a VCT solenoid is no longer working properly. 


The engine light generally has two different stages according to the severity; steady, which indicates just a minor issue, and flashing, which indicates you should immediately stop driving or get to a mechanic as soon as possible. When the light is illuminated, it simply means that something is wrong with the car – it can be as minor as a loose gas cap after filling up your tank earlier. 

  • Dirty Engine Oil

The engine oil being unclean and filled with debris is more of a cause of the VCT solenoid having issues since the VCT solenoid works best when the engine oil is clean, pure, free of debris, or lost viscosity. When the engine oil becomes clogged with debris, it can clog the passageway from the solenoid to the chain and gear. 


If the engine oil is not changed regularly and you do not have regular maintenance, it could damage that VCT Solenoid, the chain, and the gear drive all at once. 

Importance of Engine Oil

Engine oil needs to provide proper lubrication for the internal engine parts susceptible to overheating, excess friction, and rubbing against each other during use—the lubrication aids in protecting the moving parts and preventing them from excess wear and tear too early. Without the engine oil, metal-on-metal contact would damage your engine to the point of no return very shortly, leading to an expensive and extensive replacement. 


The second main reason why engine oil is vital for your vehicle is cooling the parts due to overheating. Most of the cooling required is supplied by the coolant system, like the radiator or the water pump. 

Low or Dirty Engine Oil Symptoms

Oil Warning Light – Possibly the most noticeable low engine oil symptom that most drivers and passengers notice is the oil warning light flashing on their dashboard, indicating a problem you need to take care of immediately. This suggests that you have low engine oil since there is not enough oil in your engine to run the car and power the vehicle to drive on the road. 


Knocking Noises – Another noticeable sign of low and dirty engine oil symptoms is knocking noises and loud sounds from your engine. Since these sounds will be very noticeable to everyone in the cabin, this is a symptom that is easy to recognize before the problem gets any worse. 

  • Rough Engine Idle

Usually, the VCT system does not turn on until the engine is operating at a higher and faster RPM, or if the engine is introduced to a load-bearing situation, as in if you are towing a heavy item or driving uphill continuously. However, if your VCT Solenoid is malfunctioning or not working at an optimal level, it can introduce additional engine strain and oil to the VCT gears. 


A malfunctioning VCT solenoid can cause the engine to begin idling rough, especially if the engine RPM starts to fluctuate as the system is beginning. If this issue does not check quickly, additional parts of the engine can wear out prematurely and cause more parts to break down quicker. 

Rough Engine Idle Symptoms

You can tell your vehicle is having a rough idle when cold if there is a shaking and bouncing

sensation in the vehicle, and you feel like the car is vibrating too much while your car is not moving. Although some cases are less severe than others, the rough idle is usually pretty identifiable by both the driver and passengers.


In addition to the vibrations, you might also notice strange sounds when the car is running rough idle when cold. Along with the strange sounds coming from your engine and under your hood, there might be an inconsistent engine RPM while driving and accelerating. 


Typically, a healthy vehicle will have a smooth RPM that stays at a consistent level of around 1,000 revolutions. If your vehicle is going too far below this line or moving too far above, then you might be dealing with a rough idling issue. 

  • Decreased Fuel Economy and Efficiency

The main purpose of variable valve timing is to ensure valves are open and close at the proper moments to maximize engine performance and reduce unnecessary fuel consumption, increasing fuel efficiency and miles per gallon. When the VCT solenoid is not working correctly, the entire system can start working incorrectly, resulting in intake and exhaust valves opening and closing at the wrong moments, causing the fuel economy to decline. 

Five Steps to Replacing a VCT Solenoid

Once you have figured out that you have a problem with your VCT solenoid, it is best that you can either get it replaced at a local mechanic shop and professional or if you feel confident enough to do it yourself. Not doing the proper maintenance or repairs can cause further issues with your car, like engine or transmission problems that can be easily fixed by keeping your VCT Solenoids in good condition. 


To fix the VCT solenoid, you will need some gear and equipment: service manual for your car, pry bar, pick set, sockets, ratchets, extensions, channel lock pliers, flashlight, nose pliers, dielectric grease, a box of rags, lithium grease, and telescoping magnet. 

  • Open The Hood

First, you need to open the hood and engine cover, keeping the engine hood secured so that you can have it out of your way. Second, make sure you disconnect the battery by loosening both terminals and connections, simply twisting to remove it and pull it off. Make sure you keep the cables aside and that they don’t end up touching each other. 

  • Locate the VCT Solenoid

The VCT solenoid is basically within the engine itself, located right near the valve cover. If you have the new solenoid that you will be using as the replacement, this can help you identify the faulty solenoid in your car. You will be able to see the connector at the exposed end of the VCT Solenoid and can use bungee cables to get rid of any wires, harnesses, or other parts in your way. 

  • Remove Mounting Bolts and Connectors 

After this, you will usually have to find one bolt – in some cases, there might be two. Remove the mounting bolts and store them in a safe place to make sure you have them out of the way. Next, remove the connector that you see on the solenoid and pull gently on the connector to remove the channel locks’ solenoid. 

  • Remove any Dirt or Debris and Lubricate VCT Solenoid

Once you have the solenoid, take a good look and see that the entire VCT Solenoid is out and check the solenoid mounting surface for the same, removing any kind of debris you find on the VCT Solenoid. Next, lubricate the new solenoid and the seals on the solenoid spool with the lithium grease. Then, insert the fresh VCT Solenoid into the mounting surface, using the mounting screws and tightening the VCT Solenoid. 

  • Grease the Connectors

Lastly, all you have to do now is use some of the dielectric greases, apply some on the seal of the connector's face to prevent corrosion, and rearrange anything you had previously set aside. Now, reinstall the engine cover and reconnect the battery. You have just replaced the VCT Solenoid and fixed your car from having any future expensive replacements.


We know that the VCT solenoid reduces emissions and increases fuel efficiency by enhancing the miles per gallon ratio compared to other vehicles. Due to this mechanism’s importance, you must know the signs and symptoms of a faulty VCT solenoid and the necessary replacement steps!


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