How To Pass Emissions With Check Engine Light On?

Every vehicle owner must learn how to pass emissions with the check engine light on. With the emissions test beckoning, you are wondering whether the check engine light will have an impact on the test.

How To Pass Emissions With Check Engine Light On (1)

There are many factors that determine the outcome of an emission test, and most vehicle owners are not aware of what causes a failed test. Our automotive experts provide you with an in-depth guide to help you.

What Are the Steps To Pass Emissions Test With Check Engine Light On?

The steps to pass the emissions test with the check engine light on are as follows:

  • Find the real reason behind it and diagnose the problem.
  • Perform repairs and allow the onboard computer to reset itself.
  • Have your vehicle inspected by a qualified mechanic.
  • Go for an emissions test.

Passing emissions with the check engine light on is pretty straightforward when the problem is diagnosed and necessary repairs are done.

No matter the type of vehicle you have, the procedure for solving this problem is similar. These are steps to follow to ensure your vehicle passes an emissions test even if it has a check engine light on:

1. Diagnose the Problem

You should hire a qualified mechanic to find out the underlying problem that is causing the check engine light. A flashing check engine light is a sign that your vehicle has a serious problem that can cause severe engine damage.

Diagnose Problem of Car

Ideally, a flashing check engine light is an indication that the engine is misfiring. When left untreated, this can damage the catalytic converter or your engine.

Also, the exhaust/emissions system is another cause of the check engine light. An OBD II tool can be used to identify the exact issue with your vehicle.

2. Carry Out Repairs

After identifying the exact problem, you need to carry out repairs. After repairs are done, make sure you drive your vehicle for at least 50 miles and under different conditions to allow the onboard computer to reset itself.

Also, this will allow the onboard computer to clear diagnostic codes that are stored. Make sure you have proof of repairs done to the vehicle. This may be in the form of a receipt, invoice, or other document showing repairs done on your vehicle.

3. Have the Vehicle Inspected

Before undertaking the check engine light emissions test, you should have your vehicle inspected by a qualified mechanic. This is to ensure that your vehicle is in excellent working order and that all the necessary systems are functioning properly.

Having Vehicle Inspected

4. Go for the Test

When going for an emissions test, make sure you carry with you your vehicle registration and other required documents. If the vehicle fails the emission test, you will be provided with the list of problems that were found. You need to carry out all those repairs before retesting the vehicle.

How To Turn Off Check Engine Light To Pass Emissions

To turn off the check engine light to pass emissions, if there aren’t any serious issues with the vehicle,

follow the steps below:

  • Keep driving and let it clear on its own.
  • Use an OBD2 scanner.
  • Turn the ignition on and off.
  • Disconnect and then reconnect the battery.

Sometimes, the check engine light might appear because of small problems such as the gas cap not fitting well or the need for an oil change. Having this light on is not always a big concern. If you are sure your vehicle has no serious problem, you will need to reset the check engine light.

1. Keep Driving and Let It Clear on Its Own

Sometimes, after fixing the original problem that was causing the check engine light, it can take time for the onboard computer to clear out the cycle.

Once the cycle is complete, it will recognize the diagnostic is not flagging the problem and the light goes off. If after driving for three days and the problem still persists, you will try other steps listed here.

2. Use OBD2 Scanner

Using this equipment requires some technical know-how, but it is the surefire for addressing check engine lights before emissions testing. You can also download some apps on your smartphone to run simple diagnostics. You need to plug the scanner into the OBD port that is below the steering wheel.

Using OBD2 Scanner

After turning it on, it will run the computer diagnostics and generate codes for each problem it finds. You can decipher the code with the OBD II scanner’s manual or the vehicle’s manual.

After identifying the problem and fixing it, you can remove the flag by using the “clear” or “erase” button.

3. Turn the Ignition on and Off

When your PC has a problem, you are advised to try rebooting it. You can apply the same with the onboard computer in your vehicle. The method forces the computer to return to its original state through a reboot.

Turn the ignition key on for one to three seconds and then turn it off for one to three seconds. Repeat the procedure three to four times.

4. Hard Reset Technique

In this case, you need to disconnect and then reconnect the battery. Start by disconnecting the negative terminal (usually black) and then drain the residual electricity by blowing the horn, turning on lights, or pressing the brake pedal.

Hard Reset Technique of Car

After this, you should reconnect the battery and start as usual. This method does not work for all vehicle models, especially modern vehicles that store the data in the computer even when disconnected from the battery.


– Can You Use Fuel Additives To Pass Emissions Test?

Some fuel additives such as aypanxi 05063 12 fluid ounce guaranteed to pass emissions test formula and CRC guaranteed to pass emissions test formula have proven to help vehicle owners pass smog checks. You are only required to pour a bottle of fuel additive into the fuel tank when refueling it.

– What Are the Common Causes of Check Engine Light?

The common causes of check engine light include a faulty gas cap, worn spark plugs, faulty catalytic converter, and dirty airflow sensor. Other issues include wiring problems, transmission issues, cooling systems, engine oil, and fuel system.

– What Happens if Your Vehicle Fails Emissions Test?

Failed emission test means your vehicle needs to be repaired or serviced before renewing registration. Usually, you will be given temporary registration or a grace period before retaking the emissions test. Remember that penalties vary from one state to another.

– What Is the Cost of Fixing an Emission System?

When the vehicle requires repair, the cost of repair depends on the exact problem. Replacing the exhaust system depends on the vehicle type, but the average cost is around $200.

– If You Reset the Check Engine Light, Will It Pass Inspection?

This depends on the cause of the check engine light. If it is caused by exhaust and catalytic converter issues, your vehicle will not pass.

Can a Brighter Dashboard Light Affect the Emissions Test?

Making Toyota Highlander dashboard lights brighter can potentially affect the emissions test. If the lights are excessively bright, they may cause a distraction or obscure visibility while performing the test. It is essential to ensure that dashboard lights meet the necessary requirements without compromising the accuracy of the emissions test.


You should note that there aren’t any places that will allow passing inspection with a check engine light.

Below is the summary of the most important points that we covered in the article that will help you overcome this issue:

  • Pass state inspection with check engine light on by diagnosing the underlying problems.
  • You can pass emissions with the p0420 code.
  • Try turning on and off the check engine light to get rid of it.
  • You can pass the emissions test with a bad o2 sensor.

Many vehicles fail emissions tests because of the check engine light. The sure way to pass the test is by finding out the underlying problem and having it fixed by a qualified mechanic.


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