How To Pass a Smog Test

By Subodh / March 14, 2015

Smog test is one of the procedures to ensure a cleaner and healthier environment for people. Additionally, the test also contributes to the overall performance of your vehicle. Putting it simple, smog tests are designed to measure the quantity and types of pollutants emitted by your vehicle. Besides this test, it is equally important to get other parts of the vehicle tested for smooth and efficient functioning.

Components of a Smog Test

A smog test is divided into three components and it is imperative to pass every part of the test. The components of the test include:

  • Visual Inspection – It checks emissions control systems and components.
  • Functional Inspection – This inspection checks the vehicle for proper functioning of engine light, exhaust gas recirculation system, ignition timing, gas cap and fuel evaporative system.
  • Tailpipe Emission Inspection

Smog Test

How to Pass a Smog Test

Clearing a smog test can be tough if you don’t know the tips and tricks to pass the test. There are certain pitfalls you need to avoid that can result in failure. Here are some tips that can prevent your vehicle from failing the test.

1. Don’t change the fuel type

It is a misconception among many vehicle owners changing the fuel type before a smog test would help them pass it. However, doing so would only worsen the condition. The major mistake made by people is going for a more expensive fuel type. An expensive fuel type is formulated for longer burning and not cleaner burning. It is designed for high performance engines. When used in a low performance engine, it would not cause proper burning of the fuel inside the chamber. This means that on every ignition, some amount of un-burnt fuel will be emitted by the exhaust. This would further lead to more emissions from the engine. So, avoid changing the fuel type, just before your vehicle is due for a smog test.

2. Use a fuel cleaner

Using a fuel cleaner some weeks prior to the smog test can be really helpful. This would help you keep your vehicle’s engine clean enough to pass the test. A few weeks before the test, empty a bottle of fuel cleaner into the gas tank when you go to fill fuel at the gas station. Use of fuel cleaner would help you do away with slime and grime, if any, sticking to the fuel system. It is recommended to go for a fuel cleaner that is known to reduce the level of emissions.

3. Drive more

It is recommended to drive the vehicle for a minimum of 15 to 20 minutes before you reach the smog station. The smog inspector might drive your vehicle as a part of the process. It is, therefore, important to ensure the vehicle has correct tire pressure. This would provide stability and accuracy to the vehicle when driven by the smog inspector. Also, maintenance of a steady and constant load would offer better emission output from the exhaust system of the vehicle.

4. Change the oil

If the smog test is scheduled close to the change of oil date, make sure you get the oil changed prior to the inspection. Any contaminated oil in the engine might lead your vehicle to fail the test. During this change, get your vehicle checked by a reliable technician. Make sure the Malfunction Indicator or the Check Engine light does not light up. If it does, it will result in your vehicle failing the test.

In addition to the above mentioned tips, it is best to opt for a pre-test by a reliable and certified repair shop or technician. This will let you find the issues with your vehicle prior to the test and give you sufficient time to take remedial measures. This approach will increase the chances of vehicle passing the smog test.