Honda Civic Emissions System Problem [4 Common Causes Explained]

I love Hondas due for the fact that they are extremely reliable and dependable, as a mechanic I have a lot had fewer Hondas in for repairs than cars from other brands.

However, I have recently had a few Honda Civics come in for repairs that were emissions related, and most had the same issue ” Emissions System problem” message displayed on the driver’s instrument cluster.

In this article, I am going to go through what it means when your Civic Displays “Emissions system problem”.

The main causes, and how to go about fixing the issue. let’s jump to it.

What Does Honda Civic’s “Emission System Problem” Mean?

There are two components that make up your car’s emissions system: the catalytic converter and the Exhaust.

The catalytic converter is responsible for reducing harmful exhaust gases into less toxic byproducts; it does this by using platinum and palladium as catalysts, which speed up chemical reactions in the engine.

The exhaust is responsible for releasing these less toxic byproducts from the catalytic converter into the atmosphere.

When your Honda Civic Displays “Emission System Problem,” it means the Emissions sensors detected an issue with the emission system, and that can be caused by various factors, including things that are not related to the catalytic converter or the exhaust.

Let’s look at the common causes.

Emissions System Problem on a Honda Civic Main Causes

Since there are a lot of things that can cause this fault, I decided to list them based on the most common cause in my experience.

1. Faulty Oxygen Sensors:

The most common cause I found is bad O2 sensors.

The oxygen sensor sits on the exhaust manifold and sends a signal to the ECU telling it how much oxygen is in the exhaust gas that comes out of your car’s engine.

This allows your Honda Civic to adjust its fuel delivery according to what’s needed at any given time.

If there’s too much or too little oxygen in the exhaust, then this will throw off the whole system and cause an emissions fault code.

Fortunately, this is a simple fix and the oxygen sensor only costs a few dollars. If you’re not sure how to replace this part, then I recommend heading over to YouTube and watching some videos on how to do it.

It’s not too difficult but requires some special tools like a ratchet and socket set or an impact driver that can reach into tight places.

If you are not too handy then taking your Civic to the nearest dealer should do the job.

2. Clogged/Dirty Catalytic Converter:

The catalytic converter is a device that converts harmful emissions from your car’s engine into less harmful ones.

It does this by sensing when an abnormal amount of exhaust gases are coming through and then burns off the excess so only air and carbon dioxide is left.

Honda Civic catalytic converters do get dirty and clogged over time and this can cause a few emissions and power issues, you can use a reputable catalytic Converter cleaner or have the Honda dealership do it for you which is what I recommend.

3. Dirty Fuel Injectors:

The fuel injectors in your Civic are responsible for supplying an even amount of fuel to the engine.

They do this by spraying a fine mist of gas into the combustion chambers so that it mixes with air and ignites.

If your fuel injectors are clogged or dirty, then they won’t be able to mix the right amount of fuel with air, and this can cause a few problems, including emissions in your Civic.

Fuel injectors are crucial for the engine to operate efficiently. The best way to tell if fuel injectors cause this issue is if your Honda is experiencing other issues like misfiring, vibrations when idling, and the Rpm gauge moving up and down.

Related: Honda TPMS Problem Fixed

4. Bad/Open Gas Cap:

This is not a typo, a bad gas cap can cause an emissions problem on your Civic, in fact, it is so common with civics that the gas cap goes bad and when it does it can cause a variety of issues including poor fuel economy, rough idle, and emissions.

I recommend checking your gas cap if it is still in good condition and closed as it should be.

If your gas cap is bad, I advise replacing it with one from an OEM Honda part store because they are made to fit perfectly and are made better than aftermarket ones

Can You Drive with Emissions System Problem?

The answer to that is yes, but as an experienced mechanic, I wouldn’t recommend doing that too low, since the emissions problem is caused by many things that don’t really affect the engine.

There are some causes that directly do like the injectors,  driving with faulty injectors too long can damage the engine.

I recommend taking your Civic to the nearest Honda Dealer for diagnostics and repairs.

Additional Sources:

Emission Services

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