Cars Vehicles

6 Reasons Your Car Will Fail an Emissions Test

Depending on the law in your area, certain cars should go for emission tests.

The reason these tests are conducted is to ensure vehicles do not produce excessive emissions that are harmful to the environment.

It can be surprising when you take the car for the test only for it to fail. It is a shocker especially when it has been running smoothly and has gone through regular maintenance.

In case, the reason for failure is not fixed, the car could end up unwanted. In such a scenario, the best is to sell it to a car removal company. You cannot register it when it is in such a condition.

With this in mind, what leads to a failed emission test?

An Oil Change Is Due

You have not been following your car’s manual when it comes to services. As such an oil change is due but you are still driving anyway.

This delay leads to dirty emission output as the existing oil contains numerous hydrocarbons and pollutants.

While this is not a huge problem. it should not be delayed further for optimal performance of the engine. An automaker includes how often it should be done and there are good reasons why this is so.

The only solution to this is to change the oil. The engine will be cleaner and if this is the only problem, you will pass the emission test if done again.

The Fuel Cap Does Not Seal

It could be the fuel cap cover is leaking, it is cracked, or loose. In most instances, the person conducting the test will check if the cap is tight enough.

If it has leakage, you will not pass the test. Fixing it should not be much of a hassle since all that is needed is a new cap.

Once it seals the tank properly, you can be assured this problem is sorted.

The “Check Engine Light Is On

If the oxygen sensor in the engine is broken, the car will fail the emission test without a doubt. There are no negotiations about this and if the light is on, that car should not be on the road.

It might seem like a small problem since the automobile is running smoothly but it is something not to take chances with.

Repairs can be quite expensive and if the car is old, you may consider a cash-for-cars service.

The engine consists of numerous parts and diagnosing the issue could require an expert. Leave it to a professional for proper diagnosis and repair.

The Exhaust System Is Damaged

An issue with the exhaust system could also lead to failure.

For example, if the vehicle is no longer fuel-efficient or the steering wheel and gas pedal are vibrating, there is an issue. In these cases, the engine may be noisier too.

Again, with time, just like any other part, it experiences wear and tear. If the repairs and replacements are not conducted in good time, it leads to bigger ones.

Repairing it is not all about passing the test, but also enjoying less noise and smoother rides.

A Rich Air and Fuel Mixture

Faulty injectors and an oxygen sensor with issues lead to this problem. If there is a rich air and fuel mixture, the car cannot pass the emission test.

If the inspector points this as one of the problems, your mechanic will check the two possible defective components.

A replacement may be needed but it is better than not being able to register the vehicle.

The Car Has Not Been Serviced

Servicing the car as recommended by the manufacturer is crucial. It prevents numerous issues.

Besides checking the fluid levels, other things should be changed too.

Worn spark plugs lead to incomplete combustion which in turn increases emissions. You cannot pass the test with this and they will need replacement before retesting.

The other thing that could result in a failed test is when the air filter is dirty. There is no cleaning the filter but it should be changed.

Every manufacturer has recommendations on how often it should be changed. However, with regular servicing, a mechanic can tell if a change is needed.

Other components should be changed to keep the vehicle in shape and pass the inspection. Make sure to keep up with regular servicing.

What Happens After You Fail the Emission Test?

It means that getting that car on the road is illegal. You cannot even register it or get a license plate. When this happens, what next? You should focus on making it compliant and enjoying that ride.

You will be lucky if it fails for simple reasons such as a delayed oil change or a loose gas cap. These fixes will not require a huge investment of time and money.

If it is a major issue and the check engine light will not go off, it could be expensive.

The good thing is that the inspector can give a full report of the test. They also give recommendations on what should be done.

The Car Has Failed the Test for The Second Time

The repairs have been done and you are going for a second test so you can register the vehicle. Perhaps you are confident that you will pass since all the issues you knew have been fixed.

What if you fail it for the second time? Should you give up and dispose of your vehicle? You should not despair.

In some instances, you may have to do more repairs or even be lucky and get a waiver. It will depend on the laws of your area.


An emission test is crucial to the car owner and the environment at large.

When it is conducted the owner will understand the repairs that need to be done and it helps in reducing the emissions being released.

When you get the report from the inspector, work with your mechanic to fix the problem. Even if the vehicle is old, regular maintenance will see you enjoy your drives better and pass such tests.

One Comment

  1. It’s amazing how an emissions test helps you identify if the vehicle needs repairs or part replacement. My uncle wants to revive his old muscle car for personal use, and I want to help out. We should probably look for an auto repair center where he can have it tested in the future.

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button