The oil light is on at idle: let’s look at the reasons

28.10.2019

(Votes: 1, Rating: 5)

Issues discussed in the material:

What functions does the oil pressure sensor perform in a car?
When does the oil light come on on a car?
What to check if the oil pressure light comes on at idle
How to check the oil pressure in a car

Among all types of automobile malfunctions, there are several truly unpleasant situations for the car owner, and one of these is a low pressure alarm in the oil system. What to do in this case? Should I move on or call a tow truck? In fact, the reasons why the oil light comes on at idle can be different and not always serious.

Why do you need an oil pressure indicator in a car?

Any car is equipped with indicators on the front panel that indicate the malfunction of a particular component. The oil light is red. When the engine is running at idle speed, this means that there is a problem that needs to be fixed.

Ignoring this indication may lead to dangerous consequences. Therefore, every driver should clearly know what to do when the light starts to light up.

Older passenger car models had a dashboard with a separate block with a scale that showed the current pressure in the engine, measured in kilogram-force per square centimeter (kgf/sq. cm). Accordingly, the higher this value, the higher the crankshaft speed. If the pressure dropped below the minimum permissible value at idle, the light began to light. The driver was thus notified of the presence of a malfunction.

How is the alarm system implemented in modern cars, where this scale has long been absent? Probably, some domestic models still contain a panel with this indicator. But there are very few such examples today, and all drivers need to know the standard pressure parameters.

At idle (at 800-1000 rpm), the pressure in the system, as a rule, does not fall below 0.5 kgf/sq.m. cm. Most 16-valve engines have a slightly higher threshold - 0.6 kgf/sq.m. cm. These units are characterized by high operating speeds and consume thinner oil.

To diagnose the oil system in modern cars, a mechanical oil pressure sensor is used, which, if it deviates from the norm, gives a signal and the light starts to light at idle. By the glowing indicator, the driver determines that there is a malfunction in the motor. The light flashes or stays on continuously for some time when the pressure drops below 0.4 kgf/sq. cm.

If the emergency lubricant pressure indicator lights up, you need to take immediate action to eliminate the problem. First of all, you need to turn off the engine. Even if it works normally, and the light continues to light at idle, the consequences can be dire, including engine failure. This, in turn, will mean unnecessary and unreasonable repair costs.

Since the engine is the most expensive part of the car (not counting the catalyst, which may be missing), it is better to take timely measures to prevent the unit from failing.

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The lubrication system in a modern engine plays an important role. The most important functions of the system are:

lubrication of rubbing surfaces of moving elements (pistons, crankshaft, rings, valves, liners);
partial heat removal from the combustion chamber;
flushing the resulting metal shavings into the tray;
creating a protective film on the surfaces of parts to counteract corrosion.

If the oil pressure light is on at idle, any of these functions may be impaired. Therefore, it is necessary to respond to this situation in a timely manner. The functionality of the systems will be fully ensured only when the engine is configured to optimal operating parameters. If everything is normal, the indicator will not show itself in any way.

There needs to be a good reason for the light to come on at idle. For example, a pressure drop below the minimum permissible forces the engine to work with increased load, and this is already an emergency situation. In this case, the heat dissipation function is disrupted, as a result of which the cylinder block may overheat. There is a considerable probability of complete failure of the piston group.

Engine wear

The operation of the oil pump is affected by the condition of the crankshaft. After all, it is he who causes its action. If the main bearings are worn heavily, a periodic drop in oil pressure may occur. This may be accompanied by a decrease in traction and a characteristic engine knock. If you do not fix the problem, you can get the crankshaft jammed, followed by grinding it and other delights of a major overhaul.

Conclusion

. During the operation of the engine, a variety of problems and malfunctions can arise with it. Quite often, people wonder why the oil pressure light blinks when the engine is warm. Such a malfunction can appear completely unexpectedly and requires a prompt solution. After all, poor lubrication of engine parts can lead to serious problems, including major repairs.

The other day on my Chevrolet Aveo, the oil pressure light started blinking! There is nothing good about this; in any case, it means that something is wrong with the engine. Without thinking twice, I went to the warranty service. And you know, the oil pressure light does not always blink due to a serious breakdown...

What to check if the oil light comes on at idle

If you find that the indicator lights up at idle, first of all you need to find the source of the breakdown, which you can then fix as soon as possible yourself or at the nearest service station.

Reduced oil level
Most often, the reason that the light is on is that the oil pressure in the pan is too low or the lubricant completely leaks out at idle. Unfortunately, many car owners habitually ignore the requirements of the instructions.
It states: before leaving the parking lot or garage on the road, you must check the levels of all engine fluids, including oil. The deficiency must be made up. The engine and engine compartment should be inspected regularly for leaks. When the light is on at idle, such leaks are easy to detect.
To determine the current oil level, you need to turn off the engine, open the hood and use a special dipstick equipped with marks by which the level is determined. The lack of oil will be immediately visible, and all that remains is to add fluid.
Sensor check

The emergency light located on the dashboard operates from the sensor and is powered by a wire common to it. Therefore, when the lubricant level drops below a critical level, the indicator shorts to ground, as a result of which it begins to burn. Accordingly, under normal conditions the sensor is in an open state and the oil light does not light up.
The circuit in a faulty sensor is always closed at idle speed, for this reason the indicator also lights up constantly, regardless of the current pressure in the system. If the sensor fails, it must be replaced - it cannot be repaired.
You can check the serviceability of the sensor as follows. The engine is started and warmed up, after which the lever is moved to the neutral position and the gas pedal is pressed to idle all the way, holding it until 1000-1100 crankshaft revolutions per minute are reached. If the light stops turning on, the sensor is likely faulty. To verify this, this element can be removed and a pressure gauge for measuring pressure installed in its place. A value that corresponds to the standard will mean the sensor is inoperable and needs to be replaced. If the pressure gauge reading is below the minimum acceptable level, the sensor is fine and gives the correct alerts at idle speed.
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Checking oil pressure and viscosity
High-quality engine oil has good viscosity. To check, carefully inspect the dipstick and the contents of the pan. If the lubricant is too thin, it is time to change it or it has long expired. Using liquid waste oil at idle speed and beyond leads to rapid engine wear. It is advisable to replace it at every scheduled inspection.
Problems with the oil filter.

Companies that carry out their work responsibly value their reputation. Therefore, they strive to produce the highest quality and reliable products. However, there are also “handicraftsmen” who definitely do not care about the quality of the filters produced. As a result, the market was flooded with products at very low prices.
Such filters will not be able to withstand the operating oil pressure in the engine, while modern high-quality products cope with this task quite well. This nuance should be taken into account when the oil pressure light comes on at idle. Perhaps the reason lies in a low-quality part.
After turning off the engine, the original oil filter retains a certain amount of lubricant, which makes it possible to avoid oil starvation at the next start. Cheap products do not have this function, and at idle speed the oil completely flows into the sump. In this case, there is a risk of increased wear of rubbing parts, which threatens early engine failure.
If, as a result of changing the engine oil, the indicator blinks at idle for more than 10-15 seconds, this may indicate a filter malfunction. You can verify this visually.
Oil pump malfunction
To check the condition of the pump, you will need to remove the oil pan. It is quite difficult to perform this operation without outside help, at least in foreign cars. Therefore, at idle speed, at the first suspicion of a faulty unit (the pressure light is on), it is advisable to carry out professional diagnostics at a service station.
Oil pump strainer is clogged

The mesh serves to protect the motor and pump from various contaminants (chips, dust, abrasive particles), so it is required for normal operation of the car.
Clean oil entering the pump passes freely through the filter. Contaminated lubricant with impurities clogs the mesh and penetrates through it with difficulty, as a result of which normal pressure is not maintained in the system. The oil light reacts to this and starts to light up at idle speed. To eliminate this problem, simply remove the filter, clean it thoroughly and install it back.
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Problems with pressure reducing valve
A serviceable valve is always closed, but during operation it may become stuck or jammed. In this case, it opens and becomes unable to maintain normal pressure in the oil system at idle speed, as indicated by the oil light on the dashboard starting to light up.
There are two ways to resolve this problem:
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- If the spring is stretched, it needs to be replaced.

It is necessary to regularly carry out preventive maintenance, which consists of checking the lubrication level and replacing the oil filter. You need to make sure that there are no impurities in the oil. Before changing the lubricant, the system must be flushed.

Engine wear
In engines with high mileage, oil may leak, which will cause the pressure in the system to drop at idle. Wear and prolonged use of the engine lead to greater consumption of lubricant. At the same time, strange noises arise in the engine, and the oil pressure light begins to light periodically. To eliminate the malfunction, you need to replace worn parts or perform a major overhaul of the power unit.

How to determine the quality of the auto chemicals used?

The quality of a lubricant is determined by its viscosity. The unit of measurement is centistokes. For each car, the manufacturer recommends its own optimal oil viscosity. For VAZ 2106, it is recommended to use oxol 0W or 5W in winter, and 20W and 30W in summer. If suspicion arises and inspection is not possible, the lubricant should be replaced.

This procedure is carried out as follows:

10 minutes after the engine has been turned off, you need to unscrew the plug and completely drain the lubricant.
Screw the cap back on and fill in the appropriate product.
Start the engine and let it run at minimum speed for 2 minutes.
Stop the engine and wait 5 minutes.
Check the lubricant level and top up if necessary.

How do you know which oil is suitable? First, follow the manufacturer's recommendations. And secondly, trust only well-known, well-established brands.

If the oil receiver is clogged, then it is not difficult to guess why the lubricant pressure drops. There simply won’t be enough of it supplied to the pump. If the valve breaks, the situation is different. Here, on the contrary, an increased bypass of oxol will be observed. The reason must be sought by the method of sequential elimination. First, check whether the strainer is in normal condition. If clogged, it is washed in gasoline and replaced. A valve malfunction in a VAZ 2106 car most often occurs due to a failure of the spring, which has to be replaced with a new one.

How to check the oil pressure in a car

Normal operation of the engine, both at low and high speeds, is ensured by a certain pressure of the lubricating fluid. The required level is indicated in the vehicle operating instructions. For example, the operating parameters for Priora look like this:

2 bar (196 kPa) at idle speed on a warm engine;
4.5-6.5 bar at 5400 rpm.

On average, for passenger models this value is 2 bar and 4-6 bar, respectively, at idle and at high speeds.

As already mentioned, modern cars are equipped only with a warning light that lights up at idle when the pressure drops. A full-fledged pressure gauge, as a rule, is not available. Because of this, it is often difficult to determine the cause of the indicator signal - either there is a normal lack of oil, or there is a serious problem.

In any case, there is a risk of engine damage when this light is on at idle. How to check the pressure in the absence of a built-in device? A special oil pressure gauge is used for this purpose.

The procedure for working with it is as follows:

The engine is started, which then warms up to an operating temperature of 90 degrees Celsius.
After this, the engine is turned off and the hood is opened.
Find the emergency lubricant pressure sensor and disconnect it. A pressure gauge is connected in its place. Care must be taken as the engine oil is very hot.
The device is used to determine the current liquid level. If necessary, add oil.
Then the engine is started again.
Measure the pressure first at idle, then at high crankshaft speeds.

Repeat the diagnosis 2-3 times and calculate the average value for greater accuracy of the result. Be aware that some fluid may spill out when disconnecting the pressure gauge. Therefore, it is advisable to re-measure the oil level using a dipstick after installing the sensor. If the level is insufficient, add lubricant.

How does the oil sensor work and why can it fail?

Now let's consider the situation if you are on the road and the low pressure indicator has triggered.
The very first thing you need to do is stop the vehicle and turn off the engine. As soon as it cools down, you will have to check the lubricant level in the system. There is a special dipstick under the hood for this purpose. It is wiped dry and immersed in its original place. It is quite possible that the level will be below the minimum level. This means that somewhere there is a leak or depressurization of connections. You can set off again only after adding oil to the engine. If the lamp continues to light after starting and does not go out subsequently, it makes sense to think about towing the car to the nearest service station or to a trusted auto mechanic. The matter may turn out to be quite serious, so it is advisable to conduct the examination in a calm environment. Since we have already said that the causes of low pressure may be associated with a faulty sensor, it would be useful to understand the principle of operation of this device. There are certain contacts inside it. Until the ignition is turned on, there is no pressure in the system, so the contacts are closed. When you turn the key and turn on the ignition, but before the starter starts, the warning lamp should be on. If this does not happen, then there may be some kind of malfunction. Maybe the light bulb itself simply burned out, or maybe the contacts were broken or the sensor itself failed. As soon as we start the engine, the contacts open, leading to the light bulb going out.

Oil light is on: opinions of car enthusiasts

“We need to check it consistently”
“First determine the current oil pressure in the system at idle speed and only then decide whether it is working properly or not. If the pressure is normal, the sensor is faulty. If it is low, it may be a problem with the earbuds.
Pressure problems can be solved by using additives. A friend of mine, having found himself in such a situation, filled it with phenom. The light stopped burning. He drove his car for another year and then sold it without any problems.”
“Normal oil solved the problem”
“I’ll tell you how it happened for me. There's nothing wrong with the sensor. After changing the oil, the indicator stopped flashing. And it all started when, after Liqui Moly, I poured Toyota grease into my Corolla. I did this twice and topped it up the same number of times after 7000-8000 km. As a result, I noticed that the oil pressure light was constantly on at idle. And it doesn’t just light up, it blinks. I finally decided to fill it with Liqui Moly with SMT 2, and the blinking disappeared. Yes, this is a more expensive option, but as they say, the miser pays twice.”
“I’m not particularly worried.”
“Now I don’t even look at the light bulb. It first started burning at the beginning of 2011, and with the arrival of summer it went out. Not long ago the light came on again. Apparently, the temperature outside has a big effect on it.”
“Allowed only in the first seconds of engine operation”
“A glowing indicator at idle indicates low pressure in the oil system. As the speed increases, the performance of the oil pump increases, and the pressure drops. Maybe the wrong oil was poured in, or it might be a faulty pump.
Normally, the light comes on for only a few fractions of a second when the engine starts. A working anti-drainage valve in the oil filter will not allow oil to drain, which should immediately begin to circulate through the system as soon as the engine starts. Accordingly, a certain pressure is established in the oil system immediately at idle. In my car, the light goes out and the pressure reaches the required value immediately after the starter starts rotating.”

Clogged channels

This problem may occur after repair work involving the removal of the cylinder head. Often, drivers generously lubricate the gasket with sealant for greater reliability. As a result, when the cylinder head is tightened, it is squeezed into the oil channels. If you used silicone sealant for the job, it will seal them securely. In this case, the lubrication system will work ineffectively, and the pressure will be reduced.

If this happens, you will need to disassemble the motor and clean the channels. To prevent this from happening in the future, use a dissolvable sealant, which is usually red in color and has a strong vinegar smell. Even if it gets into the channel, it will quickly collapse and will not interfere with the operation of the motor.