An EGR, or Exhaust Gas Recirculation valve, halts a portion of the exhaust gas from leaving the vehicle through the tailpipe and reintroduces it into the engine removing from it the nitrous oxide to reduce emissions. The trouble with this process is that exhaust is already hot, and it’s being recirculated into a hot engine. An EGR cooler, then, makes this less of a problem by cooling the recirculated exhaust and NOx before reintroducing it to the vehicle’s cylinders and sending the less offensive emissions out of the vehicle.
The cooled and separated gas mixture is said to increase the vehicle’s gas efficiency and lifespan because a cooler engine has to work less hard to keep all of its moving parts mobile. Most car manufacturers do not publish their findings on the tests they conduct to see ho well engines actually perform with an EGR cooler in place. Two camps have formed on the assumptions that a cooler engine performs better and the engine has to work harder to keep the cooler going and therefore the engine performance isn’t better it’s worse.
While that particular argument rages on, engine manufacturers are testing new models of EGR coolers on newer model cars. One specifically designed for diesel engines is hoped to increase diesel engine’s fuel efficiency and keep the diesel engines cooler. Diesel engines have a tendency to run hotter than standard engines, so this would be quite the boon to the trucking industry.
In the meantime, cars and trucks that are required to meet emissions regulations are equipped with the current working models of EGR valves and coolers. They have been proven to, at the very least, reduce emissions effectively, and since that’s what they were designed to do, they will continue to be installed in all present and future models of vehicles until something better comes along to replace it. California happens to be one of the states that has such regulations, and there are steep penalties and fines if your car or truck doesn’t pass annual emissions testing, cooled or not. Since most cars and trucks sold in these states are previously checked for an EGR and its cooler, only the out of state vehicle owners need to worry.