4 Common Causes of Smog Check Failure

Modern vehicles are fitted with high tech systems that allow for minimal output of emissions that are harmful to the environment as well as humans. To ensure that these systems are working properly most cars and trucks are required to complete smog checks on a bi-annual basis. These tests must be completed by a state certified smog check station to ensure quality testing and accurate results.

If it is found that your vehicle does not meet the smog requirements in California it will be necessary to have emissions system repairs completed in order to return your vehicle to a legal and safe state. These are 4 of the most common causes of smog check failure.

Failed EVAP System

The Evaporative Emission Control System, commonly referred to as EVAP, is designed to detect gasoline vapors if they are evaporating out of the filler hose. If the system fails it will result in a great decrease in fuel efficiency.

Faulty O2 Sensor

A dirty, failing or broken oxygen sensor can’t monitor exhaust correctly in order to create the proper air/fuel mixture. This can lead to problems such as a loss of engine power, overheating or jerking during acceleration. The problem that matters in relation to smog checks is that it can cause an increase in fuel use which leads to unnecessarily high emissions output.

Rich Fuel Mixture

If the vehicle is using excessive amounts of gasoline in order to run high levels of carbon monoxide will be detected during the smog check, which will lead to the failure of the test. A rich fuel mixture can be caused by leaking fuel injectors, a faulty Mass Air Flow sensor or even something as simple as a clogged air filter.

Bad Fuel Metering

In order to ensure that your vehicle runs smooth there is a system that monitors that air/fuel mixture utilized by the engine. If the computerized engine control or fuel injection unit fails or otherwise malfunctions the monitoring will be out of specification, which will lead to the failure of the smog check.

Smog checks are an important part of the vehicle’s life and are necessary to help keep it running well and ensure a healthy environment for everybody. If you have an exhaust leak, or need a smog check in Mountain View, contact the experts at A-1 Auto Tech, part of the STAR program in California.

We complete fast and accurate smog checks for gas and diesel vehicles and complete emission repairs in Mountain View on site. Give us a call today at (650) 487-2240 to schedule an appointment for a smog check or any other auto repair in Mountain View at our full service facility!