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Repair Info - Emissions Repair Explained

Causes of Excess Emissions

This section provides a little more detail on the possible causes of excess emissions. Unfortunately, some of the concepts here are quite technical. The intention is not to teach you how to diagnose emissions defects but rather to make it a little less intimidating when discussing repairs with your diagnostic technician.

If you are not familiar with any of the terms used in this section, see the Emissions Repair Glossary

Possible Causes of High Hydrocarbon (HC) Emissions

Possible Causes of High Carbon Monoxide (CO) Emissions

Possible Causes of High Oxides of Nitrogen (NOx) Emissions

Possible Causes of High Diesel Opacity (smoke) Emissions