Can Low Oil Cause Check Engine Light To Come On? [Don’t Ignore!]

When it comes to our vehicles, we all know the dreaded feeling when the check engine light suddenly illuminates on the dashboard. At that spot, you might wonder whether low oil can trigger the check engine light. In this article, we’ll explore this topic extensively and provide you with all the information you need.

So, can low oil cause check engine light come on? Low oil itself does not directly trigger the check engine light. However, low oil can lead to engine damage and other issues that cause the light to turn on. Specifically, low oil levels can result in lost compression, misfires, overheating, and dropped oil pressure. All of these mechanical problems in the engine affect combustion efficiency and can cause the check engine light to illuminate as a result. The light could also indicate issues with sensors, catalytic converter, oxygen sensor, fuel injectors or other components.

Bonus Read: Check engine light after oil change

What Exactly Is The Check Engine Light?

Check engine light is a warning signal that a car may have an issue with its engine. The check engine light is part of the onboard diagnostic system (OBD-II) which is found in all cars manufactured after 1996.

The OBD-II system is a computer-based system that is programmed to detect problems in the car’s engine. It does this by monitoring various parameters such as spark plug performance, engine temperature, and exhaust gas composition. When the OBD-II system detects a problem, it will trigger the check engine light to turn on.

The engine has a computer called ECU or PCM that monitors different operating parameters of your engine and ensure that it’s running smoothly and efficiently. The engine has a complex network of sensors that send readings to the ECU in the form of voltage signals. 

The ECU is programmed on the optimal range of those signals sent by the sensors. If the value of signals goes out of the range, the ECU triggers check engine light and your vehicle may go into limp mode.

The check engine light will remain on until the issue is fixed, or the ECU is reset. The purpose of the check engine light is to alert drivers to potential problems with their engine, so they can take necessary action before further damage is done. 

The check engine light is usually a yellow or orange-red color. If the check engine light is blinking and in red color, it indicates some serious issues with the engine which need to be addressed as soon as possible.

First Thing To Do When Check Engine Light Comes On

When the Check Engine Light illuminates, the vehicle’s ECU will generate a diagnostic trouble code (DTC). You should read the code with the help of the OBD2 scan tool to troubleshoot the problem. I would recommend BlueDriver scan tool. This is a very reliable and affordable scan tool that connects to both Android and iPhone via Bluetooth.

Sometimes, intermittent errors occur in the engine and don’t set trouble code. You can find these codes in the pending trouble codes section of the Bluedriver scan tool.

The trouble code starting from zero i.e. P0XXX, it is a generic trouble code that indicates the same problem for all types of vehicles. For instance, P0171 is a generic OBD2 code which means the system is too lean. It applies to all vehicles.

If the trouble code starts from 1 i.e. P1XXX, it is a vehicle-specific trouble code. You should enter your vehicle model name plus that trouble code in the search to find its meaning. For instance, the code P1450 has a different meaning for Ford vehicles.

Once you identify the meaning of the diagnostic trouble code that is illuminating the check engine light, you can find a specific area of the engine causing that problem. In this way, you can easily troubleshoot the check engine light problem.

Difference Between Oil Light and Check Engine Light

The oil light is a warning system designed to alert you when your engine’s oil pressure or oil level is low. This is caused by a variety of reasons, such as an oil leak, a bad oil filter, a faulty oil pump, or a broken oil pressure sensor. The Check Engine Light, on the other hand, is a much more complicated warning system that can indicate a variety of issues with your vehicle, from something as minor as a loose gas cap to something as serious as an engine misfire. The Check Engine Light can be triggered by an array of sensors in the engine, transmission, and exhaust system

The oil light is usually indicated by an icon of Aladin’s lamp with a drop of oil coming out. On the other hand, the check engine light is usually represented by an engine-shaped light bulb.

If the oil pressure is low in your engine (which is a more serious problem and the engine should be stopped instantly), the light will illuminate in red color or start flashing. If the oil level is MIN in your engine, the same indicator will illuminate, but with a yellow or orange color and a wavy line below it.

Bonus Read: How far can you drive on minimum engine oil

If there is a minor issue in the engine, the yellow or orange color check engine light will illuminate. This indicates that you can drive your vehicle to the nearest mechanic. If there is a serious issue in the engine i.e. misfire and the engine has rough idling, the check engine light will blink in red. In that case, you should immediately stop your vehicle and tow it to the mechanic.

Note: If the engine just has a low oil level, it will not turn on the check engine light. But low oil pressure is a serious problem that will affect efficient combustion. As a result, it will cause the check engine light to turn on. An engine oil light usually illuminates before the check engine light.

In What Way Low Oil Level Or Pressure Can Turn On Check Engine Light?

If the oil pressure is low due to the low oil level in the engine, it can cause the engine misfire, which will trigger the check engine light.

Low oil pressure can cause an engine misfire in following ways:

Cam Phaser Rattling

In variable valve timing engines, a mechanical component exists called ‘cam phaser’. The cam phaser is controlled by a solenoid valve to control the opening and closing of the inlet and exhaust valves. The cam phaser is hydraulically operated. The oil passes through the solenoid valve to enter passages of the cam phaser. 

When oil enters the cam phaser, it shifts the camshaft rotation to control the timing of inlet and exhaust valves.

If the oil pressure is low or the oil is dirty, it will not be able to exert sufficient pressure on the internal passages of the cam phaser. As a result, the cam phaser will start rattling. 

Furthermore, when a cam phaser rattles, it can’t properly control the timing of opening and closing of inlet and exhaust valves properly. Due to this reason, inefficient fuel combustion takes place, which will cause engine misfire. When an engine misfire occurs, the check engine light will also turn on. 

To understand better, I’ll explain everything with a visual demonstration in my guide on what happens when cam phaser goes bad.

So, if your engine is labeled as Vtec or VVTi, and your DTC trouble code says anything related to a fault in the valve timing system, it could be due to low oil pressure.

Loss Of Compression Due To Excessive Friction Between Metal Parts Of Engine

If your engine keeps on running at a low oil level, excessive friction takes place between the metal components of the engine. Apart from bad spark plug and fuel-related problems, engine misfire can also be mechanical, which takes place due to wear and tear of the engine’s components.

If the engine is exposed to low oil conditions for a long time, it will cause a loss of compression in the engine.

The first thing to understand is that the engine relies on oil to lubricate the moving parts and to keep them from overheating.

When oil levels are low, the moving parts can grind against each other and create friction, which increases the temperature of the engine and can cause it to overheat. This can lead to damage to the seals and gaskets that are meant to keep the oil in place and can also lead to a loss of compression in the engine. 

When valve steam seals and head gasket damages, the gases can leak and the combustion chamber could not be sealed properly. This will cause a loss of compression in the engine.

Furthermore, when your engine overheats, the heat can damage the pistons and the cylinder walls, leading to a loss of compression.

Another problem that can occur when your engine runs low on oil is that the piston rings can become worn out. Piston rings are responsible for keeping oil in the cylinder and providing a seal between the piston and cylinder wall. If the piston rings become worn out, the gases can escape, leading to a loss of compression. 

When the engine loses compression, it means that the air and fuel mixture in the engine cylinders isn’t getting compressed properly. This unbalanced mixture often results in incomplete combustion, which in turn causes engine misfire. Engine misfire is when the engine’s cylinders fail to ignite the fuel at the right time, resulting in a loss of power or strange vibrations. 

How Does Mechanical-Related Engine Misfire Trigger Check Engine Light?

When there is an engine misfire, fuel does not burn in a uniform manner. Engines are designed to burn in a balanced manner. The engine’s balance is thrown off and starts vibrating when one of the engine’s cylinders is not firing properly. A crankshaft position sensor is attached to the crankshaft pulley for monitoring the speed and position of the crankshaft.

So, when the engine misfires, the crankshaft rotates abnormally. As a result, crankshaft position sensor readings sent to the ECU will be out of tolerance. This will trigger the check engine light.

Furthermore, the oxygen sensor just before the catalytic converter measures the oxygen content in exhaust gases and sends signals to the ECU. If the oxygen content value is out of the range due to an engine misfire, it will also trigger a check engine light.

How To Detect Loss Of Compression In Engine?

Detecting a loss of compression in an engine is fairly simple. All you need is a compression test gauge, which is readily available at most auto parts stores.

Now, follow these steps to perform a compression test to detect loss of compression in engine:

1. First, disconnect the electric connectors of the fuel pump, fuel injectors and ignition coils/distributor.
2. Remove all spark plugs. Use a suitable spark plug socket to remove spark plugs.
3. For the first cylinder, screw the compression gauge in the hole where the spark plug goes.
4. Turn on the ignition and depress the accelerator pedal fully to keep the throttle plate open.
5. Crank the engine up to 5 times or do it until the needle on the compression gauge is peaked and doesn’t climb anymore. If you have a push start/stop button, press brake pedal and push the button multiple times.
6. Note down the pressure reading for each cylinder on a piece of paper. If you don’t know how cylinders are numbered in the engine, you can read this guide.
7. If one of the pressure readings is significantly lower, it can indicate a problem with that single cylinder. 
8. If you only have a low reading on one engine cylinder or the cylinders aren’t adjacent to each other, the issue is with the valve seal or piston ring. 
9. If adjacent cylinders have low-pressure readings, the issue might be with the head gasket.

How To Properly Check Engine Oil Level?

To check the engine oil level:

1. Park the car on a flat surface.
2. Make sure that engine is cold.
3. Pop up the hood and find the oil dipstick.
4. Pull out the dipstick, wipe it clean with a cloth or paper towel then reinsert it.
5. Pull out the engine oil dipstick. The engine oil level should be between the two marks on the dipstick.
6. Make sure that the engine oil is not dirty. Its color should be golden/brown.
7. If the engine oil level is below the lower mark on the dipstick, you should add more oil as recommended in the owner’s manual.

What If the Oil Level Becomes Low Again and Again?

You have added the engine oil, but its level becomes low again after some time, it indicates that the oil might be leaking from somewhere in the engine, or the oil is burning in the engine.

Here are the most common points of the engine from where oil leaks can occur:

• Oil pan
• Drain plug of oil pan
• Valve stem seal
• Valve cover gasket
• Rear cover seal

I’ll not go into detail on oil leaks in this guide as I have already written a guide on it. You can check my guide on oil leaks when car is parked to learn more.