Back to all

Why did my vehicle fail its emissions test?

June 9, 2025

We all want to breathe clean air and keep our planet green.  One of the ways to do that is by requiring all vehicles with internal combustion engines to pass an emissions test.  That’s because these vehicles can be big polluters.  

Everyone wants their car to pass the test so they can continue their day-to-day driving routine.  But then comes that one day when they tell you your vehicle has failed.  Why does that happen?

One of the most common reasons is that your gas cap is leaking or loose (or maybe you don’t even have one on your vehicle!).  The gas cap is supposed to seal in vapors, but sometimes its seals or gaskets dry out or crack. Replace it, and you’re good to go.

Another common reason your vehicle failed the test is that your catalytic converter isn’t doing its job. It is supposed to convert toxic gases from your engine into ones that don’t pollute the air.  There are many reasons the catalytic converter may not be working.  It may be physically damaged, or the steady flow of exhaust gases has fouled the converter. 

You may have a bad oxygen sensor. It’s supposed to measure how much oxygen is in your exhaust.  This can cause the air-fuel mixture to be too rich, resulting in too many hydrocarbons in the exhaust. Your ignition system may also have problems, such as worn-out spark plugs.  Dirty fuel injectors can contribute to excess emissions.

Believe it or not, a dirty engine air filter may be the culprit. If it hasn’t been replaced for a while, your vehicle may be emitting too many hydrocarbons -  something that will cause your vehicle to fail the emissions test.

You can usually avoid a failed emissions test by maintaining your vehicle regularly.  The best way to do that is by bringing it to our trained technicians, so your vehicle gets the service it needs, scheduled and non-scheduled.  Plus, you’ll be doing your part to keep our air clean.

Kwik Kar Saginaw
1216 S. Blue Mound Rd.
Saginaw, TX 76131
817-231-1700
http://www.kwikkarsaginaw.com

Need Service?

Request a Quote

More articles from Kwik Kar Saginaw

Kwik Kar Saginaw Advice on Buying New Tires

June 14, 2026

Today's tires and wheels offer a lot of options for every Saginaw driver's style, habits and driving conditions.Tires are designed for high-performance in winter or summer and even come in a long-wearing variety for all TX seasons.Saginaw off-roaders should be excited about the options availabl... More

Why a Trip Inspection Is a Good Idea

June 7, 2026

At Kwik Kar Saginaw we get a lot of Saginaw drivers asking about vehicle trip preparation. That's a big deal. You could be driving through mountains and deserts in some pretty lonely areas around TX, so it's important to know that the vehicle is up to the task and won't leave you stranded.Smart... More

Beware of Potholes! (Avoiding Pothole Damage)

May 31, 2026

You may live in a region where roads become pockmarked with craters known better as potholes. They're caused by moisture seeping through a compromised road surface that can freeze, expand and literally punch holes in the road. And when your vehicle hits one of those holes that's big enough, the... More