Why does my oil light come on when the car is moving?

If the oil light comes on it means a major course for alarm, which shouldn’t be ignored. I’ll explain why in a bit. For now though, let me answer the question below, which many motorists seem to grapple with

The short answer: It’s because there’s insufficient oil pressure in the engine.

More About The Oil Light

The dashboard oil light is meant to warn you about the status of your engine’s oil pressure. You see, the engine requires enough lubrication, which is only possible when it has enough oil pressure.

Without that, it can freeze or lock, causing the car to stop abruptly in the middle of the highway. The repercussions of that can be fatal if you know what I mean.

Now, the oil light collaborates with a specific sensor in your engine to monitor the oil pressure whenever the engine is running, warning you if the pressure has dropped.

I’m talking about the oil pressure sensor, which is made up of a diaphragm and a spring-loaded switch.

Now, your engine’s oil pressure monitoring system consists of the oil pressure sensor found in the engine bay and the oil light located in the dashboard.

Since it’s the sensor that does the bulk of work in the system, allow me to break it down further. That way, your understanding of how the oil light works will be greater.

The Oil Pressure Sensor

To start with, the oil pressure sensor is made up of several components just like any other sensor type in your engine. However, its two most crucial components are the spring-loaded switch and diaphragm.

The switch is wired to the engine’s oil gallery. The gallery is a series of passages cast or drilled into the engine block, crankshaft, and cylinder heads.

Their job is to receive pressurized oil from the oil pump and distribute it throughout the engine. The switch is also connected to the diaphragm, which brings us to the diaphragm.

The diaphragm is directly exposed to the oil pressure. As the oil pressure begins to drop, the diaphragm starts to take pressure in bits off of the switch’s springs.

Remember that the switch is spring-loaded. Once the oil pressure drops below the required limit, the diaphragm fully releases the pressure off of the springs.

This action closes the switch contacts, resulting in a closed circuit between the switch and the oil light. This causes the oil light to come on, warning you that the oil pressure has dropped below the safe limit.

What Causes a Drop In The Engine Oil Pressure?

A few things can cause your oil pressure to drop.

1. Having Insufficient Oil in the Engine

Your engine oil level will drop over time due to a few reasons that include leakages, evaporation, and burning. And as always, the lower your oil level, the lower your oil pressure.

Solution: Always check your oil levels at regular intervals and top up the oil if necessary.

2. Using a Poor Quality Oil

There are too many engine oil products on the market nowadays, some of which are of poor quality. The right engine oil should have proper viscosity.

In other words, it should neither be too high nor too low. If the thickness of the oil is not right, your oil pressure similarly won’t be right.

Solution: If it’s poor quality oil, replace the oil. Only use your mechanic-recommended engine oil products.

3. Excessive Engine Wear

Sometimes the oil pressure might be low despite your engine having enough oil. This is usually due to excessively worn engine parts such as bearings, especially if it’s an old engine.

Too much wear and tear in the engine can interfere with how the manufacturer designed the flow of oil throughout the engine. This can take a toll on your engine.

Solution: Replace your engine. You can buy a brand new engine or a good secondhand engine online or at your nearest store that deals in car engines.

4. A Bad Oil Pump

The oil pump plays an important role in your engine’s oil flow system. It generates the force necessary to send the oil from the oil pan to various parts of the engine through the galleries. If this component is defective, you won’t have enough oil pressure in your engine.

Solution: Replace the oil pump if it’s defective. Again, you can order a brand new pump online or from your nearest physical store that deals in such. N/B: Apart from engines, it’s not a good idea to buy oil pumps and other engine components that are used.

Is It Safe to Drive With An Oil Light On the Car’s Dashboard?

The short answer is no. When the oil light comes on, it means that your oil pressure is lower than necessary. With inadequate lubrication, your engine can grind to a halt in the middle of the highway. If that happens, a rear-end collision can’t be ruled out.

How Much Does It Cost to Fix This Issue?

The answer depends on the underlying cause;

Insufficient oil in the engine—-An engine oil can cost anywhere between tens and a few hundred dollars, depending on the brand. Nonetheless, you don’t need the services of a mechanic to top up your engine oil as you can DIY.

  • A poor quality oil—-oil replacement will set you back between $65 to $125.
  • Excessive engine wear—-A new engine can cost you thousands of dollars, depending on the make and model of your car. The same can be said for a second-hand engine.
  • A bad oil pump—A new oil pump can cost you hundreds of dollars or just over a thousand dollars.


The oil light is one of the most important warning lights a motorist should never ignore. If it comes on, you know that the oil pressure is too low and it needs to be corrected.

Without doing that, your engine can shut down abruptly in the middle of a busy highway, putting you at risk of collision. To avoid that, always check your engine oil pressure regularly.

Always fix the oil light first if it comes on before you embark on the journey, and never drive with it on.

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