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Tag: worn spark plugs

The Most Common Reasons of a Failed Emissions Test

The purpose of emissions testing is to improve air quality and reduce environmental impact. That’s why the Environmental Protection agency, also known as the EPA, sets a strict standard when it comes to emissions testing and why so many U.S. states follow suit to conduct these tests properly. If you are unsure if your vehicle meets the standards, then it’s best to have a professional take a closer look. Follow along in our blog as we discuss reasons why you could fail an emissions test.

Worn Spark Plugs

If you have worn spark plugs, this could actually lead to an increase of toxic emissions. Some of these harmful gases include hydrocarbon and carbon monoxide. Also, be sure to check your spark plug wires and replace any that look worn. Simple replacements can set you up for success to pass your emissions test.

Leaky Gas Cap

Most car owners don’t need to worry about this, but a leaking gas cap can be the culprit of a failed test. You can check for leaks before your test quite easily. If there are signs of leakage, find a cap that seals to your tank properly.

Dirty Air Filter

Clogged air filters can reduce airflow to the engine, literally choking it, and as a result affect the emission control systems of the car. It can also cause high levels of hydrocarbons, so make sure to inspect and clean your air filter before the test.

Damaged Catalytic Converter  

A damaged catalytic convert cannot do its job properly, which is to convert toxic gases to ones that are not harmful. Not only is having a broken catalytic converter bad for the environment, but it’s also another way for you to fail the emissions test.


At H.W. Automotive Inc., we adhere to a high standard when it comes to emissions testing in Oklahoma City and surrounding areas. Our certified technicians will inspect your car and ensure all emissions standards are met. Call to schedule an automotive service with us today!

How Gasoline Type Affects Your Car

gasoline pump with octane ratings

What is an Octane Rating?

Have you ever wondered what those numbers on the gasoline pump mean? You might see an 87, 89 or 91 on your gas handle, each with their own incremental price increase. These numbers are called an octane rating, which measures the ignition quality of your gasoline. The higher the number, the better the ignition quality — with one caveat. You have to have an engine that can take advantage of the higher rating. If your engine is not made to do this, you are simply wasting your hard earned cash.

Which Gasoline Octane Rating Should I Choose?

How do you know which gasoline octane rating to select? For this, you need to consult the owner’s manual. Read the section closely because wording will make all the difference. If your owner’s manual says something such as, “only gasoline with an octane of 89 should be used,” this means you definitely don’t want to go lower than an octane rating of 89, but going higher won’t make much difference to your car’s performance. If your owner’s manual says something to the effect of “gasoline with a minimum octane rating of 89 should be used in your gas tank,” this means you have the option of using 89 or higher.

What is Engine Knocking?

That may clear up what those numbers mean at the gas pump, but why is it important in the first place? Have you ever heard a knocking sound coming from your car? That knocking sound is likely combustion from gasoline igniting improperly within your gas tank. This happens most commonly when you use gas with too low of an octane rating. If you consistently use the wrong type of gas it will start to damage your engine. It’s not worth saving a few cents on the gallon to only end up with costly repairs down the road.

Engine Knocking Issues

Sometimes, engine knocking is a symptom that something is already wrong within your car. If you use high quality gasoline with the correct octane rating and still hear knocking, you will need to get a mechanic to run a diagnostic on your vehicle. The knocking may be a symptom of a malfunctioning spark plug, or perhaps your EGR (exhaust gas recirculation) system is not working correctly.

If you suspect you may have a larger issue lurking under the surface of your car’s hood, H.W. Automotive Inc can take a look and get to the bottom of the problem before it gets out of hand. Call to set up an auto diagnostic or tune up today.

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