Why Is My Check Engine Light On After an Oil Change?

Seeing that litter monster—check engine light on your dashboard can be frustrating and annoying as a car owner. A check engine light simply means there’s a potential issue in the engine.

However, if you see this warning light after an oil change, it’s not a serious issue. It’s only pointing to a minor oversight you did during the oil change, such as overfilling the engine oil and not properly seating the oil filler cap and the dipstick. While you can correct the reasons for the check engine light after oil change, it’s important to note that the warning light will not disappear immediately.

In this article, I’ll discuss the reasons for the engine warning light after an oil change, the causes, and how to reset the engine light after an oil change.

What is a check engine light (CEL)?

The Check engine light, a malfunction indicator lamp (MIL), is an essential part of your car’s onboard diagnostic system. When it appears on the dashboard, it means your car computer has detected one or more issues on your engine, emission system, or transmission unit.

What does a check engine light do?

It is a warning light that tells you of a potential issue early before it escalates to more severe and expensive-to-fix issues. The light can alert you of a minor issue, such as a loose gas cap, or a severe issue, such as a bad catalytic converter. Ignoring to diagnose and fix the cause of the engine warning light will lead to the following:

Why check engine light after oil change?

Several factors can cause the check engine light to come on after an oil change. The most common reasons for flashing check engine light after oil change are loose oil filler caps, low oil levels, low oil pressure, or using the wrong type of oil. It’s important to track the culprit and fix it correctly instead of clearing the light with a diagnostic scan tool.

Low oil level

A low quantity of oil is one of the common causes of the check engine light’s being on after changing the motor oil. For instance, if you service a car that takes 5 liters of engine oil with 4 liters, expect the warning light to come on.

Aside from the light popping up, low oil levels will cause inadequate lubrication. This will, however, affect the reciprocating engine parts.

Solutions: Check the engine oil level through the dipstick and top it with the recommended oil as needed. The oil should be at the max line on the dipstick or close to it.

Using the wrong type of oil

There are two types of motor oil (conventional and synthetic); using the wrong type can trigger the check engine light to come on. There are different oil viscosity grades, and using the wrong grade can trigger the malfunction indicator lamp on the dashboard. For instance, you should expect to see the engine warning light if you service your engine with a 10W30 instead of the recommended 0W30.

Solutions: There’s no other way to address this than using the right oil type. Drain all the oil in the engine and replace it with the recommended oil for your car.

Oil pressure issues

The oil pressure is crucial in maintaining adequate lubrication in the engine. Many factors, such as damaged oil pressure sensors, low oil levels, bad oil pumps, and leaks, can cause low pressure.

If the oil level is low or the pump is bad, the engine may not receive enough lubrication, which will cause the check engine light and oil pressure light to appear. Also, the oil pressure sensor can malfunction and send false information to the car computer, which will trigger the engine warning and oil pressure light.

Solutions: Check and fix any oil leak from the oil filter and the sump bolt. Ensure the oil pressure sensor and the oil pump are working fine. If not, fix it as needed.

Overfilled engine oil

Will too much oil cause a check engine light? Much as low engine oil will trigger the malfunction indicator lamp, excess oil will do the same. Overfilling the engine will cause reduced oil circulation, oil foaming, and increased pressure in the engine. The engine control unit will trigger the CEL to tell you what’s happening.

Solution: Check the engine oil level through the dipstick. If the oil is above the recommended mark, reduce it to the normal level by draining it through the sump bolt like you did when removing the old oil. The only difference is that you are not draining the entire oil this time. You can also drain the oil by using a suction pump.

The oil dipstick not seated properly.

The oil dipstick is the gauge used to check oil levels. Since you remove and reinsert it several times during oil changes, there is a huge chance that it’s not sitting properly. It can allow unmetered air into the engine if it’s not sitting properly. When that happens, the engine control unit will pop the check engine light.

Solution: Open the engine bay, remove the dipstick, and reinsert it properly. 

Oil filter issues

During oil changes, you should change oil filters for smooth oil filtration. Using a poor-quality oil filter is as bad as not changing the filter in the first place. Using a cheap oil filter may prevent adequate oil circulation in the engine or even allow debris and other contamination to circulate in the engine.

If, however, you do not install the filter correctly or forget to put the seal, it will cause an oil leak. Invariably, this causes low oil levels and a check engine light.

Solutions: Check the oil filter for leaks and ensure it is tightened properly. Check if you used a subpar filter and replace it if necessary.

Loose oil filler cap

The oil filler cap is the cover on top of the engine where you pour in the new oil during an oil change. If the oil filler cap is loose, it’ll allow unmetered air to enter the engine, disrupting the air-to-fuel ratio. As a result, the car computer will pop the check engine light, alerting you to check what is wrong.

Solution: Double-check the oil filler cap and ensure it is tightened correctly.

Whether you notice a check engine light after an oil change on a Toyota, Ford, or any other vehicle make and model, these are the possible causes and how to address them.

How to reset check engine light

Here’s how to turn off check engine light after oil change. First, you must diagnose the vehicle and address what caused the warning light to pop in the first place. After that, you can reset the malfunction indicator lamp with a diagnostic tool by following the below steps;

Remember, if you clear the lights without addressing the issues, the light will reappear after a few drive cycles.

Final words

Check engine light can come on after an oil change due to several reasons. Loose oil filler caps, poor quality oil filters, oil dipstick not sitting properly, low engine oil, excess engine oil, low oil pressure, and using the wrong engine oil are the possible reasons for the check engine light to appear after an oil change. It’s important to diagnose the vehicle and address the potential culprit correctly.