EGR or exhaust gas recirculation is a system that reduces emissions by returning a quantity of exhaust gases to the combustion chamber and burning it again. This system can be applied to petrol and diesel engines.
The advantages of a modern EGR system are a lower combustion temperature, higher pressure in the intake channel (better filling of the combustion chamber), the engine comes faster at operating temperature and remains this temperature. The possible drawbacks of EGR application are power loss, contamination of the intake channel, increased fuel consumption.
A malfunctioning EGR system can often be identified by poor engine running, engine retention, greatly reduced flow of intake air, leaving open EGR valve (power loss at full load, poor warm start and troubled stationary run), higher maintenance costs due to (secondary) defects and contamination, blocked and eventually defective DPF.
Often these problems can be solved by cleaning the EGR system. But in most cases this is too late and the valve is defective. Then it can replace parts (often costly, repetition of the problems can occur) or choose to disable and / or remove the EGR system (modification of software / motor electronics, combined or not with the removal of hardware) .