Nitrous Oxides are a byproduct of an internal combustion engine. It is considered one of the worst pollutants they produce. Modern vehicles are designed to reduce all pollutants in various ways. The EGR system reduces nitrous oxides by reducing the burn temperature of the combustion process. EGR stands for Exhaust Gas Recalculation. The system does just that. It takes a controlled amount of exhaust gasses and passes it through the combustion process again. This process leaves some amount of residue behind in it’s passages. After some time this residue can clog up the passages. When this happens, pollution is increased. Most modern vehicles will not pass a state emissions test with a restricted EGR system. If it gets too bad clogged up, the computer will turn on a warning light. Most modern vehicles are designed so this rarely happens. The more around town and slow speed driving that is done the more likely the system will clog up. Some vehicles may need the EGR system cleaned after 60,000 to 100,000 miles. Some vehicles may never need it. We offer this service on an as needed basis.