Honda Civic Emission System Problem

A car’s emission system is determined by the condition of its catalytic converter and exhaust mechanism. How it works is that the catalytic converter uses platinum and palladium as the source of catalysts to reduce the harmful gasses into the byproducts (with low toxins). These gasses then release the byproducts (less toxic) into the atmosphere.

Now, when we talk about the Honda Civic Emission System problem, this means that these components are not working well, and the car’s sensors have detected an issue regarding the emission of these gasses from the converter. There can be multiple reasons for this, and not resolving them can end up with potential accidents and severe injuries, even deaths in some cases.

Want to know more about the Honda Civic emission system problem, its symptoms, causes, and solutions? Keep on reading this guide.

Symptoms of the Honda Civic Emission Problem

Symptoms of the Honda Civic Emission Problem

Given the intensity of the problem, its identification is extremely important from an early stage. So, let us discuss some symptoms that can help you diagnose this problem better.

Light Indicator on the Dash

If the engine light of your Honda Civic suddenly starts flickering, it means there is something wrong with the vehicle. When it is coupled with the false sensor alarms, it is definitely an emission problem. In this case, consult a mechanic.

Fuel Smell

If you smell gas or fuel from your Honda Civic, immediately stop the car. Check for any signs of leakage. Even if there is no leakage, it is a high-risk situation, and it may result in ignition failure, so consult a professional mechanic.

Power Losses

When the Honda Civic suddenly starts consuming more power, it means that the fuel is evaporating more quickly than it should, which is probably caused by a faulty emission system. It is potentially caused by the decrease in the release of gas from the emission system.

Causes and Fixes of Honda Civic Emission System Problem

Causes and Fixes of Honda Civic Emission System Problem

Now that you know there is something wrong with your Civic, let us now discuss its causes. It will help you and the mechanic narrow down the cure options and find the best solution. So, dive right in.

Engine Issues

The first and foremost cause of the Honda Civic ECU problem is the malfunction in how the engine operates. There can be several issues with the engine, including the lack of ventilation, worn-out piston rings, faulty valve stems, and failure in the burning of oil. The only way you can diagnose these problems is through a cloud of thick black smoke that comes out of the tailpipe mixed with a burning smell.


There are only professional solutions to the engine problems. So, when you first diagnose some issue with the engine, immediately shut down your car and consult a mechanic. He can better diagnose and resolve the issue.

Catalytic Converter Failure

As I have already mentioned, the catalytic converter is essential for the efficient working of the emission system, considering that it is responsible for converting toxic gasses into less-toxic byproducts. It sends signals to the system so it can release the byproducts and burn the excess air or carbon dioxide still left in the system.

However, when these converters are used for a long period of time with no maintenance, they get dirty and clog, resulting in the release of fewer gasses. Hence, the storage of emissions in the system results in ignition failure and potential accidents. It can be fatal to the driver’s life and needs immediate assistance.


Do consider that converter failure is not always the result of clogging, and it can be the false conversion sensors. So, what’s better is to go to a mechanic for better diagnoses and solutions.

You Might Also Like To Read: Honda Civic Carplay Not Working

Clogged Fuel Injectors

Clogged Fuel Injectors

Similarly, clogged or dirty fuel injectors are equally responsible for contributing to a failing emission system in the Honda Civic. Duty of fuel injectors is to supply the correct amount of fuel to the engine. When they are used constantly with no cleaning, they mix with the air and cause problems in the ignition, hindering the emission system to release toxic gasses into the atmosphere.

When this is accompanied by other fuel injector malfunctions like loud banging noises, misfiring, sudden vibrations, and the RPM surging constantly, it is critical. In this case, you immediately need to consult a mechanic.


If the problem has not yet worsened and you are able to figure it out from the start, it is easily resolvable. All you need to do is use a vacuum pump and clean the air filters in the ECU system. However, if the problem is intense and it is followed by the above-mentioned symptoms, it is better to consult a professional dealer.

Faulty Oxygen Sensors

Faulty Oxygen Sensors

Lastly, another common reason for the Honda Civic’s emission failure can be the faulty oxygen sensors in the vehicle. It occasionally happens that the sensors are sitting on top of the exhaust manifolds and send signals to the ECU so the system can figure out how much oxygen is left in the system. In response, it adjusts the fuel delivery for the required time.

However, if there is too little or excessive oxygen in the exhaust system, it sends false signals to the system.


Resolving this issue requires repairing the sensors or replacing them entirely, but the good thing is that it won’t cost a lot of money. Even better, you can do it yourself, as all it needs is a ratchet, socket, and a tutorial. However, if you have no experience with the vehicle, consult a professional mechanic.

Read Also Our Experts Guide About: Honda Civic Bluetooth Not Working

Final Thoughts

Honda Civic ECU problem has been reported to impact the drivers and even cause severe injuries. It can result in accidents and even deaths, which is why it is better to evaluate its causes and find potential solutions. I hope this guide has helped you in understanding its occurrence and solution.

Thank For Reading!

Related Articles:-

Similar Posts

Leave a Reply

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