A vehicle can fail an emissions test due to a bad or low-quality catalytic converter because the converter is crucial in reducing harmful pollutants emitted from the exhaust system. Replacement can be a costly repair, but it is best to ensure it is a quality part rather than risk replacing it multiple times. Here’s why:
- Increased Emissions: The catalytic converter’s primary function is to convert toxic gases like carbon monoxide, nitrogen oxides, and hydrocarbons into less harmful substances such as carbon dioxide, nitrogen, and water vapor. If the catalytic converter is malfunctioning or damaged, it won’t effectively convert these gases, leading to higher levels of pollutants in the exhaust. This increase in emissions will typically cause the vehicle to fail an emissions test, as it will exceed the acceptable limits set by environmental regulations.
- Check Engine Light: Many vehicles are equipped with onboard diagnostic systems that monitor the performance of the catalytic converter. If the converter is not functioning properly, the system may trigger the “Check Engine” light. During an emissions test, the presence of a lit “Check Engine” light can automatically result in a failed test, as it indicates a potential problem with the emissions control system, including the catalytic converter.
- Incomplete Combustion: A failing catalytic converter can also affect engine performance, leading to incomplete combustion of fuel. This results in higher levels of unburned hydrocarbons being released through the exhaust, which will be detected during an emissions test, further contributing to a failed result.
Common signs of a failing converter before the check engine light are the vehicle can be sluggish engine, rotten egg smell or sulfur, dark exhaust or extreme heat for under the vehicle. Repair costs can vary from $500 to $3000 depending on the vehicle. There will always be cheaper options, but you will also get an aftermarket that may not be as efficient.
In summary, a bad catalytic converter leads to higher emissions, potential engine performance issues, and a triggered “Check Engine” light, all of which can cause a vehicle to fail an emissions test. Regular maintenance and timely replacement of a failing catalytic converter are essential to ensure that your vehicle passes emissions tests and remains environmentally compliant.