Why Oil Light Comes On and Off But Oil is Full? (Fix Now)

Oil is necessary for an engine to function properly. Another thing that is crucial is an uninterrupted flow of oil. Fortunately, modern vehicles come equipped with useful features like an “oil light on the dash” that alerts us to how smoothly the oil is flowing. There are three possible scenarios.

When the light is off, it means oil pressure is normal. If it is on, most likely  oil pressure is low. What about when the light comes on and off even when the oil is full. Don’t worry, only a few things need to be checked, which  include a faulty oil pressure sensor, wiring to the oil pressure sensor, and a bad oil pump.

Keep reading; we will have a detailed discussion on why the oil light comes on and off when the oil is full.

What Causes Oil Light Comes On And Off But Oil Is Full?

Similar to how blood must flow smoothly for a person to function properly, engine oil must also flow smoothly. The smooth flow of oil keeps the internal combustion engine safe. With the proper oil pressure, oil will flow to all areas of the engine, reducing friction between internal parts. 

When the engine has a lack of fuel, it may result in low oil pressure, which in turn means the oil light comes on. On the other hand, it is possible that the oil tank is full but the oil light is still on when it ought to be off. 

The situation is a little different from the typical low oil pressure warning light, but not difficult to handle. If you have a similar problem, you must be wondering, then, what are the root causes of the issue? Well, here is a list of the common reasons, and you must look into them.

  • Faulty oil pressure sensor
  • Faulty wiring of the oil pressure sensor
  • Bad oil pump
  • Faulty oil pressure switch

Solutions For Oil Light Comes On And Off But Oil Is Full

Since the oil is full and the issue does not appear to be with the oil level, the reasons we mentioned earlier are to blame. We will describe each factor in detail.

1. A faulty oil pressure sensor : Replace the oil pressure sensor

The oil pressure sensor is a small part and is often overlooked. It measures the oil pressure of the engine. When the pressure changes, so does the voltage or the resistance of the sensor, which is then indicated by the PCM (powertrain control module). 

When the PCM finds any discrepancy, it stores the DTC code. Some vehicles may have an oil pressure sensor switch that closes when the pressure drops.

When the oil pressure sensor is defective or the switch malfunctions, the malfunctioning sensor or switch may mistakenly signal a low oil pressure condition, which will ultimately cause the oil light to illuminate.

The best strategy is to diagnose the sensor. Carry out the resistance test, which is easy since the sensor comes with one or two pins. If you find that the sensor is defective, the best course of action is to replace the censor.

Depending on the make, model, and year, the average cost of an oil pressure sensor is somewhere between $50- $100. If you include the cost of the labor, then the cost will increase a bit. The time to replace the sensor is around 1 hour.

2. Faulty wiring of the oil pressure sensor: Repair or Replace the Faulty Wiring

This is yet another factor to consider. When the wiring to the oil pressure sensor is loose or defective, it may not be able to send some current to the oil light when it is necessary. So the light is off when it should be on.

Alternatively, when the wiring connecting the oil pressure sensor or wiring connecting to the oil pressure switch is loose, there is a chance the loose wiring will short out, which may cause the oil light to come on.

Therefore, you must visually check every piece of wiring coming from the sensors. Examine the wiring to see if it has any burnt or damage. Replace them if you find any as necessary.

3. Faulty Oil Pump: Replace the Faulty Oil Pump

When the oil pump does not work, oil pressure gets low even if the oil tank is full, which causes the oil light to come on. 

The sole purpose of the oil pump is to circulate oil throughout the engine. When a pump malfunctions, it is unable to perform its function, which reduces oil flow and causes the oil light to come on even when the oil tank is full.

A lack of oil in the engine is a common cause of oil pump failure. Since in our case, the engine is full, it is most likely the pump itself is defective. It does not matter whether the oil tank is full or empty.

There are a few indicators that the fuel pump is faulty, such as oil pressure lights turning on, engine overheating, noise, and difficult starting. You must replace the pump as soon as you are certain that it is defective.

The cost depends on the cost of the labor and the cost of the replacement parts. When it comes to the cost of the parts, the average cost for the replacement parts is somewhere between $400 to $450. And the cost of labor is around $750 to $1000.

4. Faulty Oil Pressure Switch: Replace the Switch

When the oil pressure switch is defective or the switch malfunctions, it may mistakenly signal a low oil pressure condition, which will ultimately cause the oil light to illuminate even if the oil is full. On the other hand, the oil light is off when it should be on.

Unlike the oil pressure sensor, which communicates with the ECM, the oil pressure sensor is directly connected to the oil gauge. The switch is located near the air filter, whereas the sensor is located near the oil pump.

An oil pressure switch monitors the oil pressure level and sends the information to the oil gauge on your dash. When it finds the pressure level is too low,  the oil light on the gauge turns on. This is if the switch works properly.

However, when the switch is faulty, as previously said, it may mistakenly send a false signal. The light turns on when it should be off. Alternatively, the light is off when it should be on. The best way to fix the problem is to replace the faulty pressure switch. 


On Oil Light Comes On And Off But Oil Is Full

Hopefully, you have your answer by now. We made an effort to cover the majority of pertinent points. Here are a few frequently asked questions that you might find interesting.

Is It Safe To Drive With An Oil Light Flickering?

Light flickering itself is not an issue. The question is, why is the light flickering ? It is because the engine oil pressure is not right.
Since the steady oil pressure is good for engine health, it is better if you do not drive for a long time. Get your vehicle to the garage and solve the issue.

What Causes The Oil Pressure Light To Turn On?

Besides the reasons we have described earlier, there are many other reasons for the oil light turning on. 
Worn out internal engine components 
Engine overheating 
Lack of oil 
Worn out oil
Air filter is clogged 
Oil viscosity

What Do I Do If My Oil Pressure Light Comes On And Off?

Well, when the light is on, most likely it is a low oil pressure light, so you must check the oil level.
If the oil is full but still the oil light is on or intermittent (comes on and off), then the most likely culprit is one of the following: faulty sensor, oil pressure switch, or faulty wiring  to the sensor.

What Are The Symptoms Of Low Oil Pressure?

The most obvious symptom is that the oil light on the dash will turn on. The other symptoms of low oil pressure include engine overheating, reduction in fuel economy , engine stalling, and difficulty starting the engine. You may also hear the bad noise from the engine.


A slightly different and less likely scenario involves the oil light turning on and off intermittently. Most often, if not always, you will likely see that the oil light is either turned on or off. 

Off simply means that oil is flowing as it should, whereas on means that there is a low oil pressure problem that needs to be fixed.

And when the oil light flashes intermittently (turns on and off), the causes of the oil light coming on could be different. There could be other causes as well, but the ones we’ve already mentioned are most likely to be to blame.

We make an effort to answer all of your pertinent questions regarding why the oil light flashes when the oil is full. Hopefully, you have solved the issue.

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