Check Engine Light After Oil Change – Causes, Prevention and Fix

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Your car’s check engine light after oil change is an important warning indicator that something is not functioning properly within the engine or emissions control system. If the check engine light turns on after an oil change, it can be concerning and frustrating. While there are many possible causes for the light to turn on, an oil change should not be one of them. In this post, we will discuss some of the reasons why your check engine light may have turned on after an oil change, how to prevent it from happening in the future, and how to fix the issue.

Possible Causes of Check Engine Light After Oil Change

There are a few reasons why an oil change may trigger the check engine light to turn on. Some of the most common causes include:

Oil Leak

One possibility is that the oil filter was not installed properly or the drain plug was not tightened enough, or due to a damaged oil pan which can lead to an oil leak. If the engine is losing oil pressure due to a leak, the check engine light may turn on.

Unmetered Air

Another possibility is that during the oil change, a component of the air intake system was disturbed, causing an unmetered air leak. This can throw off the air/fuel ratio and cause the check engine light to turn on.

Faulty Sensor

A faulty oil pressure sensor can also trigger the check engine light to turn on. If the sensor is not maintaining a normal oil pressure, it may send incorrect readings to the car’s computer and illuminate the light.

Dirty Air Filter

A dirty air filter can also trigger the check engine light to turn on. During an oil change, the mechanic may inspect the air filter and find it needs to be replaced. However, if the filter is not replaced, it can cause the check engine light to turn on.

Wrong Oil Type

Using the wrong type of oil can also trigger the check engine light to turn on. Different vehicles require different types of oil, and if the wrong type is used, it can cause issues with the engine and trigger the light.

Prevention

To prevent the check engine light from turning on after an oil change, there are a few things you can do:

Choose a Reputable Mechanic

When getting your oil changed, make sure you go to a reputable mechanic who will install the oil filter and drain plug correctly. It’s also a good idea to check reviews and ratings before choosing a mechanic.

Replace Faulty Sensors

If a faulty sensor is causing the check engine light to turn on, it will need to be replaced. This can be done by a mechanic or a knowledgeable DIYer.

Replace Dirty Air Filter

If the air filter is found to be dirty during the oil change, it should be replaced. A dirty air filter can cause issues with the air/fuel ratio and trigger the check engine light.

Use the Right Oil Type

Always use the correct type of oil for your vehicle. Check your owner’s manual or consult with a mechanic to determine the correct type of oil for your car.

How to Fix Check Engine Light After Oil Change?

If the check engine light illuminates after an oil change, you may be tempted to ignore it, but this could lead to further complications. Here are some steps to follow to fix the check engine light after an oil change.

Check for Oil Leaks

The first thing you need to do is to check for oil leaks. If you notice any oil leaks, you need to fix them immediately. If the oil leaks onto the engine, it can cause the engine to overheat, which can trigger the check engine light. You should also check the oil filter to make sure it is correctly installed.

Inspect the Oil Pressure

Low oil pressure can also trigger the check engine light. You can check the oil pressure using an oil pressure gauge. If the oil pressure is too low, you may need to replace the oil pump or the oil pressure sending unit.

Check the Air Filter

A dirty air filter can cause the engine to run too rich or too lean, which can trigger the check engine light. If the air filter is dirty, you need to replace it.

Check for Unmetered Air

Unmetered air is air that enters the engine without passing through the Mass Air Flow (MAF) sensor. This can cause the engine to run lean, which can trigger the check engine light. You can check for unmetered air by inspecting the intake manifold gaskets, vacuum hoses, and throttle body gasket.

Check the Spark Plugs

Worn or damaged spark plugs can cause misfires, which can trigger the check engine light. You should inspect the spark plugs and replace them if they are worn or damaged.

Inspect the Oxygen Sensor

The oxygen sensor measures the amount of oxygen in the exhaust and sends the information to the engine control module (ECM). A faulty oxygen sensor can cause the engine to run rich or lean, which can trigger the check engine light. You should inspect the oxygen sensor and replace it if it is faulty.

How to Reset Check Engine Light After Oil Change

  1. Ensure the vehicle is parked in a safe and stationary position with the engine turned off.
  2. Locate the OBD-II (On-Board Diagnostic) port in your vehicle. It is typically located under the dashboard on the driver’s side. Consult your vehicle’s manual if you’re having trouble finding it.
  3. Take an OBD-II scanner or code reader and plug it into the OBD-II port. These devices can be purchased or sometimes borrowed from an auto parts store.
  4. Turn the ignition key to the “On” position without starting the engine. This will power up the scanner or code reader.
  5. Use the scanner’s interface or buttons to navigate through the menu options and select “Read Codes” or “Scan for Codes.” This will retrieve the diagnostic trouble codes (DTCs) stored in the vehicle’s computer.
  6. Once the codes have been read, look for an option in the scanner’s menu to clear or reset the codes. Select that option to clear the codes from the vehicle’s computer.
  7. Disconnect the OBD-II scanner from the OBD-II port.
  8. Start the vehicle’s engine and check if the check engine light is no longer illuminated. It should have been reset by clearing the codes.

Please note that while this procedure may clear the check engine light temporarily, it does not address any underlying issues that may have caused the light to come on in the first place. If the light comes back on after the reset, it is recommended to have the vehicle inspected by a qualified mechanic to diagnose and address the underlying problem.

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