When you change the oil in your car, you expect the check engine light to go off, but sometimes, it doesn’t. This can be frustrating, especially if you’re confident everything was done correctly. In this article, we’ll explain various reasons why the check engine light may remain on after an oil change, and provide you with step-by-step instructions on how to reset it.
Why Does the Check Engine Light Stay On After an Oil Change?
After changing your oil, there are a few reasons why your check engine light might stay illuminated. Understanding the root cause is important to resolving the issue before attempting a reset. Here are some of the most common reasons:
1. Improper Oil Level
Too much or too little oil can cause the check engine light to stay on. Overfilling can create pressure issues, leading to misfires and oil foaming. On the other hand, if the oil level is too low, it could trigger the engine’s warning system due to lack of lubrication.
Solution: Check the oil level using the dipstick and adjust as necessary. If overfilled, remove the excess oil using a suction pump or drain plug. If it’s underfilled, simply add more oil until it reaches the proper level.
2. Incorrect Oil Grade
Using the wrong type of oil can also cause problems. Modern engines are highly sensitive to the viscosity and type of oil. A mismatch between the oil’s grade and the engine’s requirements can cause engine performance issues, leading to a check engine light.
Solution: Drain the incorrect oil and replace it with the recommended grade according to your vehicle’s manual.
3. Loose or Missing Oil Cap
Forgetting to replace or properly secure the oil cap is a frequent mistake. The oil cap is responsible for maintaining pressure inside the engine and preventing unmeasured air from entering. A loose or missing oil cap can lead to improper air-fuel ratios, which may trigger the check engine light.
Solution: Check if the oil cap is tightened properly or if it’s missing, replace it immediately.
4. Unseated Dipstick
The dipstick measures your engine’s oil level, and if it’s not properly seated, air can enter the engine and cause the check engine light to activate. This is a common issue during oil changes.
Solution: Reinsert the dipstick securely into its housing and ensure there is no debris obstructing it.
5. Faulty Sensors
If the check engine light remains on, it could be due to a faulty sensor that was not reset during the oil change. Modern cars have sensors that alert you when it’s time for an oil change. These sensors should automatically reset once the oil is changed, but sometimes they need manual intervention.
Solution: Use an OBD-II scanner to reset the sensor (instructions below).
Step-by-Step Guide to Resetting the Check Engine Light
If you’ve addressed the causes mentioned above and the check engine light is still on, here’s how to reset it:
1. Use an OBD-II Scanner
The Onboard Diagnostic (OBD) scanner is a tool that reads and clears error codes from your car’s computer.
- Step 1: Locate the OBD-II port under your dashboard, usually near the steering wheel.
- Step 2: Plug the OBD-II scanner into the port.
- Step 3: Turn the ignition on without starting the engine.
- Step 4: Allow the scanner to read the diagnostic trouble codes (DTCs).
- Step 5: Review the codes using your car’s manual to confirm there are no unresolved issues.
- Step 6: Use the scanner to clear the codes, which will reset the check engine light.
This method is highly effective, and most auto shops offer OBD-II services if you don’t have the tool yourself.
2. Drive for a Few Miles
Sometimes, the car’s computer needs time to recalibrate after an oil change. Simply driving for a few miles may reset the check engine light automatically.
3. Disconnect the Battery
If an OBD-II scanner isn’t available and driving doesn’t help, you can disconnect the car battery to reset the system.
- Step 1: Turn off the engine and disconnect the negative battery terminal using a wrench.
- Step 2: Wait for about 15 minutes.
- Step 3: Reconnect the battery and start the car.
This will clear the car’s memory, which may reset the check engine light. Keep in mind that this method also resets other electrical settings, like the clock and radio presets.
Final Tips for Preventing Check Engine Light Issues
Here are a few tips to help avoid future issues with the check engine light after an oil change:
- Always use the correct oil grade and viscosity as recommended by your vehicle’s manual.
- Double-check the oil level before closing the hood to ensure it’s neither too high nor too low.
- Secure the oil fill cap and dipstick to prevent air leaks into the engine.
- Regularly inspect your car’s sensors and replace faulty ones to prevent unnecessary warning lights.
Troubleshooting Persistent Check Engine Lights
In some cases, even after resetting the check engine light, the issue might persist. This could indicate a deeper problem that requires professional attention. Here are some additional factors to consider:
1. Faulty Oil Pressure Sensor
Sometimes, the oil pressure sensor itself is faulty, causing the check engine light to remain illuminated even when everything else is in order. This sensor monitors the oil pressure in the engine and sends a signal to the car’s computer if it detects anything unusual.
Solution: A faulty oil pressure sensor should be replaced. You can diagnose this issue by having a mechanic check the sensor using an OBD-II scanner or through a manual pressure test.
2. Catalytic Converter Issues
The catalytic converter is responsible for reducing harmful emissions from your vehicle’s exhaust system. If it becomes clogged or damaged, it can trigger the check engine light. This is often the case if you notice a loss of power, rattling noises, or poor fuel economy.
Solution: A catalytic converter must be replaced if it’s clogged or damaged. Unfortunately, this is one of the more expensive repairs, but it’s essential for maintaining your vehicle’s performance and complying with emission regulations.
3. Damaged Oxygen Sensor
The oxygen sensor monitors the level of unburned oxygen in your car’s exhaust. If this sensor malfunctions, it can lead to improper fuel mixture and increased emissions, which will illuminate the check engine light.
Solution: Oxygen sensors usually need to be replaced every 60,000 to 90,000 miles. Have your mechanic check the sensor if it hasn’t been replaced recently.
4. Mass Airflow Sensor Failure
The mass airflow sensor measures the amount of air entering the engine and helps regulate fuel injection. If this sensor fails, the engine may not get the correct fuel-to-air ratio, which can result in poor fuel efficiency and cause the check engine light to stay on.
Solution: A mechanic can clean or replace the mass airflow sensor. Regular air filter changes can help prevent this issue from occurring in the first place.
The Importance of Regular Vehicle Maintenance
Regular vehicle maintenance plays a critical role in preventing check engine light issues. Changing your oil on schedule, using the right oil grade, and checking your vehicle’s sensors and filters can significantly reduce the likelihood of seeing that dreaded light.
- Routine oil changes: Follow your vehicle’s recommended oil change intervals to ensure smooth operation.
- Keep an eye on sensors: Periodically check your oil pressure, oxygen, and mass airflow sensors to catch issues early.
- Check other engine components: Ensure that vital parts like the catalytic converter and air filters are in good condition.
By staying on top of these maintenance tasks, you’ll avoid unnecessary trips to the mechanic and keep your vehicle running efficiently.
Stay Proactive and Solve the Problem
By understanding the reasons why your check engine light stays on after an oil change and taking the right steps to reset it, you can prevent any unnecessary stress and keep your car running smoothly. Whether it’s a quick adjustment to the oil level or resetting the sensor using an OBD-II scanner, these steps will help you address the issue confidently.
Tags: Check engine light troubleshooting, How to reset engine warning light, Reset check engine light after oil change