WHAT IS AN EGR VALVE?
Exhaust Gas Recirculation (EGR). Is a valve used to reduce harmful NOx emissions, which operates by recirculating a regulated percentage of the engine’s exhaust back into the air intake, which prevents the NOx gas from forming in the first place?
WHAT ARE THE BENEFITS AND DISADVANTAGES OF EGR SYSTEMS
Modern engines recirculate some of their exhaust gases back into the engine with the aim of reducing emissions. This is the is the main benefit of the EGR system. The downside is that exhaust fumes containing carbon deposits are constantly being recirculated through the engine through time causing a build-up of carbon deposits in the intake manifold etc.
These deposits sometimes contribute to the failure of the EGR system itself. Replacement EGR valves can be expensive and in the case of high mileage engines the continual carbon build up can eventually lead to total engine failure.