Oil Light on When Idling – What Is The Reason?

Last week I had a new car roll in the shop with a common problem on models older than ten years, an engine oil light on, only when the car is idling.

There wasn’t a car shaking when idling.

Why Does Oil Warning Light Come on When Idling?

A low engine oil level is the most apparent reason, but it wouldn’t cause the warning to turn on only when the car is running.

A loss of oil pressure caused by a malfunctioning oil pressure sending unit or a bad sensor would be a more reasonable cause for an oil warning light.

Here is a list of the most common issues that can cause an oil light to turn on.

Oil Light

Faulty Oil Pressure Gauge

The pressure may be optimal, but the oil pressure sensor isn’t. This problem with older cars is something I see a lot.

The check gauge light will come on when there is a problem with the car. After 10 to 15 years, your car is more likely to have electrical issues and cause false readings.

I suggest taking your car to a repair shop or a dealership and having a technician check your oil pressure using a mechanical oil pressure gauge.

If there is a loss of oil pressure, this will tell us. If there is no pressure loss, you will be happy to know that your problem is a bad sensor, which is not very costly to fix.

Worn Bearings

The worn crankshaft and camshaft bearings are likely to be the cause of the problem.

As the years go by, worn-out engine components cause the oil to flow easier and the pressure to decline. The oil light will go off if the flow increases and the oil pressure increases.

If the crank journals are not worn out, you can get them fixed with a new set of bearings. It can be quite expensive if you don’t have an oil pressure test.

What Symptoms Do Worn Engine Bearings Have?

The loss of pressure is the result of worn bearings. This is usually indicated by the oil pressure light on your dashboard.

If you pay close attention to the start of the car, you can identify worn engine bearings. It is possible that your engine bearings need to be replaced if the engine makes a noise.

If your bearings start to wear out, there will be no noise.

Not Enough or Old Oil

I tell my clients that they need to take care of their cars to avoid big bills. A lot of potential problems can be prevented by having your oil changed frequently.

I recommend doing an oil change every 12 months or 8,000 miles, whichever comes first. You can prolong the life of your engine by making sure you have clean oil.

There is a chance that the car is leaking oil and preventing the pressure from building up.

The oil change needs to be done correctly by the mechanic. If you don’t add enough oil, your oil light will come on.

Wrong Engine Oil

The correct oil type is so important that I can’t stress it enough. If you are doing the oil change yourself, you should read the car manual to make sure you use the right type.

The higher the oil’s viscosity, the harder it will be to flow through the engine in the winter. If you’re certain that you used the correct oil type, then you should exclude this possibility.

Worn-out Oil Pump

It isn’t very common, but I have seen it happen in the past. A malfunctioning oil pump can cause oil flow to drop. This would be the last thing to be looked at as it can be expensive.

Faulty Pressure Switch

Sometimes a bad oil pressure switch can send a false signal, indicating low oil pressure, even if it isn’t the case.

What to Do When Your Oil Pressure Light Comes on?

As soon as the oil warning light comes on, you should stop driving. If the distance is not long, contact a repair garage and either have it towed or drive there.

Attach a mechanical gauge to your engine to check for oil pressure drops if the oil level is okay.

You will most likely need to replace the bearings if the mechanical gauge shows a low oil pressure while the car is idling.

If the engine oil pressure is normal, the problem is a lousy sensor or a faulty gauge which is the cheapest outcome for you.

If the oil pressure is not high when the car is running, you will need to replace the oil pump. Depending on the make and model, it can cost between $600 and $800.

Running low on oil or using the wrong type of oil can cause irreversible damage to your engine if you don’t use the right oil.

How to Prevent This?

It is easy to prevent issues with your car if you have it serviced by a competent mechanic on time.

It’s important to use genuine parts approved by the manufacturer when servicing your vehicle.

If you purchase a second-hand car, make sure it has a full-service history and check to see if the previous owner kept it in tip-top shape.

As car engine repairs will be costly, it’s better to take every prevention method to avoid them.

I recommend addressing the problem as soon as possible because things can get out of hand quickly.

Oil Light


I would start by checking and replacing the easy parts, such as the pressure sensor because there can be multiple causes for the oil warning light.

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