Some might argue that the most important fluid in any car isn’t fuel, but instead, that golden ember of oozing liquid we call, motor oil. Sure, your car might not drive without any fuel. But at least, the engine won’t try to destroy itself within mere minutes. Hence, proving once more, the importance of engine oil. This is proven by your need to care for and look after your motor’s oil control valve.
Granted, oil control valves aren’t found on every car, just those few whose engines feature variable valve timing. If you’re familiar with Hondas, that’s VTEC, for you. It’s an ingenious solution to further maximize an engine’s performance, without making a dent in fuel economy or raising emissions. As with any piece of new tech, however, innovation can add complexity that you’ll have to worry about.
One such example is the presence of an oil control valve. Sitting at the very top, it controls how much oil to pass through to the camshafts. This is a big deal since variable valves don’t operate at a fixed pattern, requiring this valve to carefully manage the flow of oil. Without it, you could experience an abundance of woes, like poor performance, bad mileage, or worse, catastrophic engine damage.
- What Is VVT?
- What Does It Do?
- Causes Of Failure
- Fixes And Costs
- DIY Replacement
- Final Thoughts
What Is Variable Valve Timing (VVT), Anyway?
So, what does an oil control valve do, then? First, let’s start with the basics. In your engine, you’ll find something called a camshaft. Placed on top of the cylinders, the camshaft is a long rod, with a series of lobed, egg-shaped “cams”. When the engine is running, the camshaft coordinates its rotation with the crankshaft (at the bottom of the engine) depending on the movement of your pistons.
This timing is driven either by the timing belt or the timing chain. As the pistons begin to fire up and down, the camshaft gets to work with supplying the combustion chamber with more fuel and air to burn. At the same time, it’ll need to get rid of exhaust fumes. To do this, the camshafts will open and close either the intake or exhaust valves. It manages this with the aforementioned lobed cams.
The intake valves allow fuel and air to enter the combustion chamber, to then be ignited and provide power. Once that’s done, the exhaust valve will open up to suck out all the fumes from the cylinders, as the whole cycle repeats. Your engine’s camshaft will open and close the intake and exhaust valves at a constant timing, by milliseconds. This is set by the manufacturer for its most ideal setting.
Although, variable valve timing has become quite popular in recent years. In other words, the timing of when to open and close the intake and exhaust valves respectively are no longer fixed. It can now do so on the fly. In short, a VVT system can open or close the intake and exhaust valves much sooner or later than traditionally demanded. Thus, improving performance, without sacrificing gas mileage.
What Does The Oil Control Valve Do?
Variable valve timing is a marvel of modern automotive engineering and a subtle way to make cars go faster, but without any penalties or compromises in regards to valve timing. For example, you’re able to get up to speed much faster at lower RPMs. Or, allow the engine to work more efficiently by carefully supplying the right amount of fuel, whenever it’s needed. This is all thanks to one part.
And that would be an oil control valve. In every variable valve timing system, there’s such a thing as the oil control valve. See, VVT systems manage the timing of the intake and exhaust valves by simply adjusting the angle and positioning of the camshafts. This is all controlled by your car’s ECU (engine control unit), which takes in input from the throttle pedal, engine speed (RPM), and so forth.
In order, as you step on the accelerator, the ECU gets to work with adjusting the valve timing as best as it can. It sends electric signals to the oil control valve (sometimes abbreviated as the OCV). As this happens, the OCV takes in already available motor oil in the engine. When the valves open, the high hydraulic pressure of the oil is used to change and actuate the angle or position of the camshafts.
In doing so, the pressurized oil aids in adjusting and optimizing the timing of the opening and closing of the valves. Depending on how fast your car is driving, the OCV can advance (open and close the valves earlier) or retard (open and close the valves later) as is necessary. The OCV can do all of this rapidly, and seamlessly. Plus, the OCV also aids in improving lubrication, as well as cooling with fresh oil.
What Causes An Oil Control Valve To Fail?
Most automakers have their own take on variable valve timing. The most popular of which is Honda and Acura’s VTEC, or their newer i-VTEC. Ford’s equivalent is called VCT, whereas Audi has Valvelift, and Mitsubishi takes pride in its MIVEC engines. Subaru calls theirs either AVCS or AVLS, depending on the engine in question. Meanwhile, Toyota has VVT-i, and so on. There’s one constant, though.
Given time, with enough use and abuse, the oil control valves could fail. However, failure of the OCV on its own is rare, as the most common cause of the malfunction is bad or old oil. As time goes on, your engine oil can break down due to intense exposure to heat. Not to mention, oil can attract impurities or small debris within the engine. Combined, your oil will soon thicken into a thick, black sludge.
This is mitigated with regular oil changes, ensuring that you always have slick and fresh oils in your engine. Unfortunately, more than a few people sometimes neglect or delay oil changes, allowing this sludgy oil to circulate much of the engine. Once it gets too thick and viscous, there’s a likelihood that this oil can’t even flow through the oil control valve. Hence, causing it to clog up and block oil flow.
Eventually, the oil control valves fail altogether. Other typical root causes of OCV failures can include corroded electrical connections, which carry input to the unit. Alternatively, the OCV may break if the VVT solenoid (which takes in signals from the ECU to centrally manage the actuation of the valves) is the one that’s failed. Otherwise, oil control valves are designed to last the lifetime of your vehicle.
What Are The Symptoms Of A Bad Oil Control Valve?
When the oil control valve does give way, it’s imperative that you get it fixed promptly. While a bad oil control valve won’t scrap the engine immediately, it’s not recommended to keep on driving. The many symptoms (which we’ll discuss in a bit) will make your driving experience unpleasant. There’ll be the usual consequences of performance penalties, increased fuel economy, and poor driveability.
If you leave it be for too long though, all of this could add up to permanent engine damage, which is far more costly and complicated to mend than a broken OCV. Therefore, our recommendation is to get a faulty OCV sorted right away. Use the engine’s power, while it’s still driveable, and head over to a nearby workshop. And, do so as quickly as you notice any one of these symptoms…
1. Rough Idle (Your Car Shakes And Vibrates More While Idling)
Ordinarily, your engine’s VVT system is designed to work quietly and smoothly in the background. Its operation to alter the valve timing may become noticeable when you add more load to your car. For example, driving at higher RPMs, hard acceleration, overtaking other cars or going up a hill.
Otherwise, the VVT will usually remain inactive. This isn’t the case, however, if the oil control valve is on the verge of failing. When it happens, you’ll immediately notice a rough idle. This describes a feeling of shakiness, with more vibrations and unrefined sounds as the engine is merely idling.
The sensations are combined with seeing your engine speed (RPMs) fluctuating constantly. As you’re driving, rough idle will assuredly compromise your car’s performance. In more extreme cases, it may even cause your engine to stall in the middle of a drive.
Bad oil control valves cause rough idling through their inability to provide the right amount or pressure of oil when needed. For instance, retarding the valve timing so much, that your RPMs begin to tank. Or, either starving the VVT of oil or flooding it with far too much pressurized oil at once.
2. Poor Performance (Noteworthy Sluggishness And A Lack Of Power)
Continuing onwards, a bad oil control valve would also contribute to a lack of acceleration or power. Remember, a VVT system is designed to improve performance. When the OCV (a core part of every VVT system) fails, it will consequently affect the ability of your engine to alter its valve timing.
It would not be able to best optimize the engine for optimal power and torque. The valve timing may be off, as the camshaft angle or position isn’t in its most ideal setting. Without it, the effects will be readily noticeable. You’ll especially feel sluggishness under heavy loads, such as accelerating.
3. Engine Misfiring Or Knocking (Odd Sensations From The Engine)
A significantly more serious issue that could be caused by a faulty oil control valve is either knocking or misfiring in the engine. First, the knocking. This is a scenario described as a pre-detonation, where fuel is ignited and burns before it can sufficiently mix in with air.
Or to put it another way, a premature ignition, far sooner than anticipated. This could both cause a significant drop in performance, as well as waste away fuel. If it’s escalated to a point where the knocking has gotten so bad, it might even cause long-lasting damage to the engine.
Another alternative scenario is misfiring. This is what happens when fuel is either burned poorly or has failed to ignite at all. Misfiring can affect the entire engine or individual cylinders. We identify misfires with poor performance, difficulties starting, popping noises, or a lot of smoke.
When it comes to the OCV, it can cause misfires or knocking thanks to the position of the camshaft. If the camshaft angle position is stuck too advanced or retarded, it might prompt the valves to open or close at the wrong time. Thus, preventing your engine’s air-and-fuel mixture from burning properly.
4. Check Engine Light (Warning Lights On The Dashboard)
As it’s connected to the ECU (your car’s central computer brain), it’s capable of alerting you of a bad oil control valve very early. Your ECU constantly monitors the state and wellbeing of your car’s many components, and could readily analyze if a part has failed, or if it’s not working right.
If the ECU detects a problem, it’ll warn you by illuminating the check engine light. You can then plug in an OBD diagnostics tool to extract and read into any error codes thrown by the ECU. Among the error codes that might appear due to a failed oil control valve include (but isn’t limited to):
- P0010 – Intake Camshaft Position Actuator Circuit/Open (Bank 1)
- P0011 – Intake Camshaft Position Timing – Over-Advanced (Bank 1)
- P0012 – Intake Camshaft Position Timing – Over-Retarded (Bank 1)
- P0013 – Exhaust Camshaft Position Actuator Circuit/Open (Bank 1)
- P0014 – Exhaust Camshaft Position Timing – Over-Advanced (Bank 1)
- P0015 – Exhaust Camshaft Position Timing – Over-Retarded (Bank 1)
- P0020 – Intake Camshaft Position Actuator Circuit/Open (Bank 2)
- P0021 – Intake Camshaft Position Timing – Over-Advanced (Bank 2)
- P0022 – Intake Camshaft Position Timing – Over-Retarded (Bank 2)
- P0023 – Exhaust Camshaft Position Actuator Circuit/Open (Bank 2)
- P0024 – Exhaust Camshaft Position Timing – Over-Advanced (Bank 2)
- P0025 – Exhaust Camshaft Position Timing – Over-Retarded (Bank 2)
- P1381 – Variable Cam Timing Over-Advanced (Bank 1)/Misfire Detected
- P1382 – Variable Cam Timing Solenoid 1 Circuit Malfunction
- P1383 – Variable Cam Timing Over-Retarded (Bank 1)
- P1384 – VVT Solenoid A Malfunction
- P1385 – Variable Cam Timing Solenoid B Malfunction
- P1386 – Variable Cam Timing Over-Advanced (Bank 2)
- P1387 – Variable Cam Timing Solenoid 2 Circuit Malfunction
- P1388 – Variable Cam Timing Over-Retarded (Bank 2)
5. Overheating Engine (Lack Of Oil Flow For Cooling)
Remember, the oil control valve doesn’t just manage pressurized motor oil to change the positioning and angle of the camshafts. As the oil control valves open, fresh oil is circulated through the valves, camshafts, solenoids, and many other constituent parts of a variable valve timing system.
Thus, providing a secondary form of cooling (besides the coolant) by funneling heat from these parts into the oil pan, where it can be cooled. If and when the oil control valves fail, it may prevent oil from flowing into these components, causing them to run hotter, and the engine to overheat.
6. Increased Fuel Consumption (Gradually Lower MPG Figures)
One of variable valve timing’s most beneficial traits is its ability to minimize fuel consumption, while also maximizing performance. It does so by carefully predicting and managing the valve timing, as it ensures that as little fuel is used as possible. And, for every drop to be burned to great effect.
When your oil control valve breaks, so too will your engine’s VVT. Therefore, diminishing any upside to fuel economy. The valve timing is no longer in sync, as the intake and exhaust valves may open or close sooner or later than ideal. This may lead your engine to burn a lot more fuel than is required.
How Much Does It Cost To Fix A Bad Oil Control Valve?
Having now understood what to look for with a bad oil control valve, what can you do to fix it? Alas, an oil control valve can’t so easily be fixed, and it’s recommended to get it replaced outright. On top of that, and in some cars, the oil control valve is integrated with the VVT solenoid as a single unit. A replacement of the OCV will, in that case, require you to replace the entire VVT solenoid, as well.
The cost to replace a bad oil control valve is approximately $100 to $600. Breaking it down, you can find oil control valves (including a VVT solenoid) for about $50 to $300. Meanwhile, labor costs will add another $50 to $300 to the final bill. On average, you can somewhat expect a replacement cost of around $200 to $500, but this will vary widely depending on the make and model of your vehicle.
If your car requires using high-grade or specialty oil control valves, it would increase the cost of parts required. In addition, and if your oil control valves are difficult to access, they might also incur a higher labor charge. Besides replacing the OCV and VVT solenoids, there are several other costs to take into account:
- Diagnostics ($50 to $100) – Charged by a mechanic (not always applicable), to diagnose and identify the issue at hand. Often, this covers the cost of scanning for trouble codes and inspecting the OCV.
- Oil Change And A New Filter ($30 – $150) – If the OCV failed due to burnt-out, contaminated, and old oil, you’re also recommended to flush it out. Then, top up your car with fresh oil, and install a new oil filter. This will help to clear out the oiling system of sludge.
Can You Manage A DIY Oil Control Valve Replacement?
Although not cheap, the overall sum of replacing an oil control valve isn’t as expensive as some other parts of a car. However, there are many DIYers and tinkerers who are always keen to get down and dirty by getting it done at home. So, can you replace a faulty OCV by your lonesome, DIY-style? Yes, but seeing how it’s not as terribly pricey to get it fixed at a workshop, a DIY solution isn’t necessary.
Still, and if you prefer to wrench on your cars, it’s not impossible to replace them. Oil control valves, and the VVT solenoid that it’s a part of, are located within the cylinder heads, near its camshafts. In some cars, they feature two VVT solenoids, one for the intake valves, and the other for the exhaust valves. Most cars, on the other hand, have just one, often located near the intake side of the valves.
However, some automakers install the VVT solenoid(s) and OCV inside of the engine’s valve cover. It can make a replacement process more challenging, as it requires a more thorough disassembly. In general, replacing a VVT solenoid and OCV involves:
- Disconnecting the battery to shut off all electrical supply.
- Locate the variable valve timing solenoid (the oil control valve should be a part of it).
- Remove the mounting bolts, and remove the VVT solenoid.
- Lubricate the replacement solenoid, and apply some sealant to it.
- Re-seat the new solenoid, and reattach the mounting bolts.
- Reassemble the engine cover, and reconnect the battery.
- Give your car a short test drive, and see how it performs.
Final Thoughts On Oil Control Valves
That then is a great place to round up our thoughts on oil control valves. In summary, and while they may not appear as consequential as they are, they’re every bit essential for your engine to function. But only, if you have an engine with variable valve timing. Oil is pressurized, which effectively alters the angle and positioning of the camshafts, thus varying the timing of the opening or closing of the valves.
It’s very important to get this timing right, and for the OCV to function properly. Otherwise, you’ll be experiencing poor performance, a rough engine, as well as decreasing fuel economy. Worse, and if you don’t get that faulty oil control valve solved in time, it could lead to permanent engine failure. This will cost far more than a replacement OCV, which often comes with a VVT solenoid.
Replacing it isn’t the most expensive repair job in the world, as far as cars are concerned. And, know that oil control valves aren’t designed to break that quickly. They’re made to last the lifetime of any car, and only fail when you forget to get the oil changed in time. All in all, preventive maintenance is a cheap and effective way to never have to worry about a failing oil control valve, ever again.
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