Check Emission System Acura: What’s the Solution?

When you see “check emission system” on your dashboard, then there is a problem under the hood.

It could mean that your fuel cap is loose or there is a problem with your vehicle’s emissions or fuel evaporative system (EVAP). In this state, your MDX will release more emissions than is allowed by Federal standards and as a result, may fail an emissions inspection. This is for those in those states where routine emission tests are required.

This could happen to your Acura MDX, ILX, TL, RDX, or TSX. So, if you have any of the aforementioned vehicle versions, then you are not alone.

Quite a lot of people are experiencing the same problem as you. Fortunately, there is a solution to it, so keep reading.

Check Emission System Acura: Code to Look for

The code for “emission system check” is P0420.

Diagnosing your car and check the code:

One of the essentials of a car owner is a car scanner. When I first got my car, I didn’t have a car scanner. So, when I would go to my mechanic for a fix, he would sometimes miss the point.

Since I use the internet a lot, I started looking for solutions online and came across the recommendation to get a car code scanner.

I got one and every time I get a code and check it online, I know what’s wrong with the car and what to fix. This not only saved us from “throwing parts” but also the time and stress of going back and forth.

So, I recommend you get a car scanner when you can and get the code yourself so you know what’s wrong with your car and the LIKELY COST of a fix before going to your mechanic.

Why is this important?

Some dealerships can charge you up to $120 just for a single diagnosis. Unfortunately, if you don’t know, you would think it’s a normal thing. I’ve paid for one in the past.

With your own OD2 scan tool, you’ll be able to get a code for the problem and that code will tell you the faulty component, which would then make diagnosis easier for you.

Also, you only have to buy your scan tool once and they aren’t that expensive. Finally, you can use Autozone to check the code for free…

How to Solve Check Emission System in Acura

There are two ways you can solve this problem, depending on your budget, time, and experience. This is broadly divided into two:

  • DIY
  • Appointment with your dealership

In both cases, you’ll likely spend time or budget or it could be both. Usually, I like to go the DIY route especially if it’s an easy fix.

This is how I am able to fix most of the problems in my vehicle and now understand a lot about how my vehicle works.

So, if you are patient and have some time to spare, I’ll recommend the DIY approach first.

But if you’re afraid of spoiling something or complicating the problem or just don’t have the time, then you’re free to set up an appointment with the dealership.

The DIY Approach: Fixing It Yourself

DIY Solution #1: Check Fuel Cap

The first thing you want to do is check your fuel cap is well-tightened. If it wasn’t tightened enough, then your vehicle can throw the “Check Emission System Warning” light. This often happens when you just add fuel to your car.

So, remove and retighten the cap until you hear 5 clicks. Then follow by 5 ignition restarts. This should solve the problem if it’s a loosely tightened fuel cap.

Note: In addition to the Check emission light, you may also see “tighten fuel cap” come up.

That will make it easy to since you’ll know exactly what’s wrong. But if you don’t have this second warning, then the other solutions in this article might help.

Why is this?

Your vehicle has a + vapor recovery system. When the cap isn’t tight, the pressure will become too much, causing the warning sign to come up. And since the VES is only for emission, you’ll the warning for emission.

Also, it is stated in your manual (if you check) that the light will go off after 3 days after you tighten the cap. So, if it’s been two days and it’s still there, you shouldn’t become impatient.

DIY Solution #2: Be Careful When Refilling

Most of the vehicle users who have had this problem say it comes up in between refilling, which syncs well with the solution above. In one way or another, the gas cap isn’t being well-tightened.

So, while this is related to the above, I wanted to call your attention to this. Since this can happen a lot during refilling, you may want to pay more attention.

Also, if you can have a full tank each time you refill, that will reduce the chances of this problem coming up.

DIY Solution #3: Reset the Error

What if you’re in a state where it’s not required to do routine emission tests? Well, you’re in luck. What you can do is reset the error yourself and clear it from your dashboard.

Usually, it’s not a serious problem since some people say that it comes and go by itself. Also, if you fix your car sometimes, it may still show the light even and only resetting the code may clear it.

For this, you’ll need an OBD2 Scanner.

They are plenty on Amazon for cheap. Some are even $10, just make sure the one you buy has 4.5 stars or above. Order one and reset the code and the light should go away.

Note: A related fix is disconnecting the battery’s negative cable and waiting 5 minutes before connecting it back. This will essentially drop the error code from the system.

DIY Solution #4: Change Catalytic Converter/02 Sensor

While the first two solutions are easy fixes, this might not be so easy. It may be that you have a bad catalytic converter. When your catalytic converter is faulty, your MDX may throw this warning sign.

If you can change it yourself, then it’s the next place to look. However, if you’ve not done it before and cannot follow a Youtube video to get it done, then it may be a fix you want to leave for your dealership to handle.

Expect to pay anything from $250 upwards to replace your catalytic converter at the mechanic.

Note: If you can order the part yourself and bring it to them, that might save you some cost. But it’s not compulsory.

Fixing An Appointment with Your Dealership

As you can see from the above, most of the fixes are very simple. Which I believe most people should be able to handle.

But sometimes, due to time constraints or lack of experience, most people would rather opt for a mechanic to handle it.

The advantage of knowing these things, however, is that you know what your mechanic/auto shop/dealership is most likely going to do to fix your car. You’re well-informed.

That should help you negotiate better. And if the next dealership is far from you, you can ask the right questions before going there.

That will save you the time of going there without getting the problem solved.


Why is my Acura showing “Check Emission System?

Simple answer: It could mean that your fuel cap is loose or there is a problem with your vehicle’s emissions or fuel evaporative system (EVAP)

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