Why Your Acura Failed An Emissions Test & How To Fix It

by Mechanics Direct February 9, 2025

Emissions tests are an essential part of vehicle maintenance, helping your car to operate efficiently while minimizing its environmental impact. If your Acura has failed an emissions test, you might find yourself frustrated and also wondering ‘what next?’ Understanding the common reasons behind an emissions test failure and how to fix them can help you get back on the road quickly, while also keeping your vehicle running at its best.

What Is an Emissions Test?

An emissions test measures the amount of pollutants your vehicle releases into the atmosphere. The results help to make sure that your vehicle is in alignment with state regulations regarding air quality and environmental standards. If your Acura fails the test, it lets you know that the levels of one or more of these pollutants exceed the allowed limits.

Common Reasons Your Acura Failed an Emissions Test

The oxygen sensors in your Acura monitor the amount of oxygen in the exhaust gases and send this information to the vehicle’s engine control unit (ECU). The ECU uses this data to adjust the fuel mixture for the best combustion. If an oxygen sensor malfunctions, the fuel mixture isn’t going to be correct and that can affect your emissions. A faulty oxygen sensor is one of the most common reasons a vehicle fails an emissions test.

You may have heard of the catalytic converter which is a part that helps to reduce harmful emissions. It converts toxic gases like carbon monoxide and hydrocarbons into less harmful substances, such as carbon dioxide and water. As time goes on, the catalytic converter can become clogged or worn out, reducing its ability to filter emissions. You can end up with a failed emissions test if this part isn’t working in tip top shape!

The mass air flow sensor measures the amount of air entering the engine and provides this information to the ECU. This helps the engine adjust the air-fuel mixture for combustion. If the MAF sensor isn’t working the way it should, the engine may receive incorrect readings, which could lead to improper combustion and higher emissions.

An issue with your fuel system, such as a malfunctioning fuel injector, can lead to incomplete fuel combustion. When the engine does not burn fuel efficiently, it results in excess emissions. Problems with the fuel pressure regulator or fuel pump can also contribute to poor fuel system performance, causing the vehicle to fail its emissions test.

Vacuum hoses play an important role in controlling the engine’s air intake system. If one or more vacuum hoses are cracked or leaking, the engine may not be able to control the air-fuel mixture properly. This can lead to poor combustion and increased emissions.

That pesky check engine light (CEL) can let you know that something is wrong with your vehicle’s emissions control system. The CEL is often triggered by a variety of issues, including problems with sensors, the catalytic converter, or the fuel system. A glowing check engine light is one of the most obvious signs that your vehicle may fail the emissions test.

Sometimes, general engine wear or a malfunction can lead to excessive exhaust emissions. For instance, if the engine is burning oil, it can produce a higher volume of pollutants than usual. Regular maintenance is essential to ensure that your engine remains in good condition and passes the emissions test.

How to Fix the Issue and Pass the Emissions Test

The first step in fixing the issue is to get a diagnostic test to identify the root cause of the problem. Mechanics will use diagnostic tools to read the vehicle’s error codes and pinpoint the specific component or system that is causing the emissions test failure. This can save you time and money by addressing the exact problem rather than making unnecessary repairs.

If the oxygen sensors are found to be faulty, replacing them is a quick and easy solution to your problem. New oxygen sensors will restore the proper air-fuel mixture and help your Acura run more efficiently, reducing emissions.

If the catalytic converter is worn out or damaged, it will need to be replaced. This is a more expensive repair, but once it is taken care of, you’ll be passing your emissions tests again!

If the MAF sensor is malfunctioning, it may need cleaning or replacement. A properly functioning MAF sensor will ensure that the engine gets the correct air-fuel mixture for optimal combustion.

If the issue is related to the fuel system, such as clogged fuel injectors or a malfunctioning fuel pressure regulator, these parts should be repaired or replaced. Restoring proper fuel system function will help improve combustion and reduce emissions.

If leaking vacuum hoses are causing the issue, replacing them will restore proper engine performance and reduce emissions.

Regular maintenance, including oil changes, spark plug replacements, and air filter replacements, can help keep your Acura running smoothly and prevent emission-related issues from developing in the future.

Get Expert Help at Mechanics Direct

If your Acura has failed an emissions test in North Chelmsford, Chelmsford, Dracut, Tyngsborough, Westford, Lowell, or surrounding areas, Mechanics Direct can help you out and get your Acura back into working order! Our skilled technicians specialize in diagnosing and repairing all types of emissions-related issues, ensuring that your vehicle passes the test and runs efficiently.