Bad VVT Solenoid (Causes, Symptoms and Fixes)

Bad VVT Solenoid

The VVT solenoid (view on Amazon) is now a must have for modern car engines following the standard for multi-valve technology in engine design. Unless you’re a gear head, you probably don’t even know what a variable valve timing (VVT) solenoid is. Nonetheless, your car has one, and when it malfunctions it causes big trouble your system. If you suspect you have a bad VVT solenoid, or you just want to know all about one, read on to find all you need to know.

Variable Valve Timing (VVT) Solenoid

The variable valve (VVT) solenoid, also known as the oil control valve, is an important part of the variable timing system in your car bas it does all the thinking for the other valves and helps the engine breathe. The valve is designed with high precision springs, windings, screen filters, OE-matched harness connectors, and high performance coatings.

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The VVT solenoid is attached to the camshafts that open and close the valves near the cylinder head block and the timing change or belt cover. The timing of the engine air/fuel intake is regulated by the phase angle and shape of the cams. The VVT works by electricity to regulate the camshafts. The valve measures the engine’s needs based upon the oil pressure using camshaft phasing sockets and oil pressurized solenoids to regulate the timing of valve lift events within the RPM range.

The VVT solenoid regulates the flow of oil based upon the engine load and engine speed. The valve controls how long the different valves in the engine remain open based on the engine requirements. Engine valves regulate the amount of air enters the engine and how much exhaust leaves. When the engine is idling, it does not require as much fuel. Thus, the engine requires less intake of air. The exhaust can be retained to minimize the amount of air that enters the engine during the idle.

Less fuel is burned which promotes fuel efficiency. When an engine must produce enough power to run uphill at a high speed, more fuel is required. More specifically, the engine needs more of the air/fuel mixture. The VVT solenoid must open the valves as wide as they can go and for as long as is needed to achieve a large amount of power. The engine must also expel a larger amount of exhaust. Thus, the VVT solenoid opens the exhaust valve as wide as it can go for as long as is needed to maintain the speed and pressure.

Causes of VVT Solenoid Failure

The design and manufacture of VVT solenoids are high precision, high quality processes. So, why would a VVT solenoid ever fail? The parts to your engine move fast in very harsh, heated conditions. The engine temperature and flow of oil has to operate a specified level. The VVT solenoid is so important that when it fails, many other parts are in jeopardy. Here are the most common causes of VVT solenoid failure:

Wear and tearExcessive wear on a vehicle combined with time can cause anything from worn bearings to reductions in the original flow restrictions. The components of the internal combustion engine get dirty with deposit buildups over time and passages become blocked after excessive use. No matter how expensive, any vehicle is subject to problems due to wear and tear over time. The VVT solenoid is electric and uses solenoids that are oil pressurized. The oil pressure is influenced by wear or high mileage and a lack of vehicle maintenance.

Cheap, low grade oil – The quality of the oil (view on Amazon) is very important to your engine’s performance. Oil sensitivity to water emissions increases or decreases depending on the quality of the engine oil. Elements that cause engine sludge include cheap, low grade engine oil followed by oil contaminated with dirt, coolant, blow-by, fuel, excessive heat, and acid. The manufacturer recommends the best oil for your car; however, the choice of brand is up to the driver. The most high quality engine oil is transparent with the right additives. It is free flowing and free of any debris, water, and fuel. On the other hand, cheap, low quality engine oil, like API SA, is unstable and can ruin even the strongest engines.

No oil change – Internal combustion engines required several quarts of clean oil in order to operate smoothly and efficiently. If the intervals between oil changes is too long, or the oil is not changed at all, the result is low and high oil pressure problems. Over time, the quality and quantity of oil is naturally reduced due to the infinite heating and cooling cycles. When the oil is not changed in your vehicle at the recommended intervals, you get the same results as using cheap, low quality oil. With time, old oil becomes contaminated with the same pollutants. The dirty oil then coats the cylinders, which causes heat buildup and more stress over time.

Engine sludge – As oil heats up, it leaves behind carbon deposits. Carbon deposit buildup in car systems over time. Excessive engine heat and debris begin to oxidate engine oil, which changes the oil’s structure. The oil then becomes thick and sticky like a gel and things begin to attach to it which cannot fit through the oil filter. The engine sludge also loses most of its heat tolerance and burns through some of the parts it becomes attached to. When the oil passages finally become clogged with sludge, the engine can fail. After the sludge has covered certain parts and solidified, the engine will have to be replaced.

No Maintenance – Most vehicle owners understand that a vehicle must be inspected and serviced from time to time, as referred to as routine maintenance. For those who don’t, the likelihood of problems that cause the VVT solenoid to go bad is extremely high. If the vehicle is not inspected routinely, small problems can escalate to major problems that are much more expensive to fix. This is also true for vehicles which sit for long periods of time.

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Symptoms of VVT Solenoid Failure

When the VVT solenoid is functioning, it reduces the harmful emissions from the exhaust, improves the engine performance and also the fuel efficiency. However, when it is not functioning properly, there are signs that something is wrong. Here are the most common symptoms of VVT solenoid failure:

Check Engine Light (CEL) activated –- When the VVT solenoid goes bad, the check engine light (CEL) may activate. This will especially occur in newer model cars with sensors when the powertrain control module (PCM) detects a problem. The CEL could also be activated for other reasons as other circuits also trigger the CEL. If the oil warning light is activated along with the CEL, you know you’ve got trouble.

Oil Pressure Warning LightMost cars have an oil warning light on the dash. When you first start your car, the needle should start out at high, as the oil pressure is highest when the temperature is cold. When the oil pressure reading is high, the needle moves to high where the warning light will activate.

When oil pressure becomes too high or low, the oil warning light should activate. This could mean the engine oil is too viscous as when the oil becomes dirty, it loses viscosity. The oil pressure warning light in newer vehicles is attached to sensors that report any irregularities. When the oil warning light activates, it’s time to have the car inspected for problems associated with the oil pressure, which includes the VVT solenoid. Note: Sometimes, an oil gauge has become damaged and will then produce false readings of high or low oil pressure. Make sure your oil gauge is working and giving accurate readings.

Rough idle – Rough idling is one of the more common symptoms of trouble with the VVT solenoid. The VVT system activates when the engine reaches higher RPMs, or when the engine is presented with heavy load tasks like driving uphill. If the VVT solenoid is not working, more oil is presented to the VVT gears. The engine RPM begins to vary when the VVT system is activated causing the rough idle. The car may run with a failing or bad VVT solenoid for a while, but the handling will be rough when you drive. When you come to a stop, the engine will idle roughly.

Decrease in fuel economy – The more fuel that is pumped to the engine, the less mileage your car get per gallon of fuel. The VVT solenoid has the job of making sure the valves open and close only at the most advantageous times. When the VVT solenoid does not regulate the openings and closings with the correct timing, the amount of fuel intake may exceed what is really needed for the job. The fuel economy will be significantly reduced.

How To Replace the VVT Solenoid

Once you’ve discovered that the VVT solenoid has gone bad, it can be replaced with a few tools and little effort. This section will guide you through the process:

1. Gather the tools you’ll need and the correct replacement VVT solenoid. You will need the service manual for your car; sockets; an 18 length pry bar; lithium grease; dialectic grease; pick set – long set; telescoping magnet; ratchet; ¼ ratchets and ¼ sockets; ¼ extensions 3 and 6; 12 bungee cords; a box of rags; channel lock pliers and needle nose pliers; and a flashlight.

2. Park in a safe place.

3. Turn the engine OFF and open the hood of your car.

4. Disconnect the battery by loosening both terminals. Use a bungee cord to secure the terminals and keep them apart.

5. Find the VVT solenoid. It will be located close to the engine. Look at the connectors on the replacement solenoid to know what to look for.

6. When you locate the VVT solenoid, use a bungee cord to clear the wires in the space.

7. Find the mounting bolts and carefully remove them. Place the bolts in a safe place.

8. Disconnect the VVT solenoid and remove it. Disconnect the connector and use the channel locks to pull and twist the metal parts.

9. Make sure that all of the component and its pieces are fully removed from the space. Use the needle pliers to remove any debris.

10. Lubricate the new VVT solenoid. Then lubricate the insertion point with lithium grease.

11. Insert the new VVT solenoid in the proper space and shift it.

12. Secure the new solenoid by replacing the mounting bolts and tightening them.

13. Apply dialectic grease to the face of the connector to preserve it once it is reinstalled. Install the connector.

14. Reconnect the battery.

15. Try your new solenoid out. Give your car a spin and see if the symptoms persist.

Go to the Repair Shop – Changing the VVT solenoid can be a big challenge if you are not familiar with auto parts. If you got lost in the instructions for replacing the VVT solenoid, you can still take your car to a professional repair shop to have the VVT solenoid replaced. It is very important that the replacement be done right. Regardless of the price, get that solenoid replaced and drive safe.

Job Guthiri is a freelance writer with 3 years of experience writing for Motorsrun and other established automobile outlets. His focus and key interests are Tacomas and maintenance. Read our Editorial Guidlines and Fact Checking process.