The Exhaust Gas Recircularisation Valve is an invention to reduce emissions at idle by recirculating a portion of the exhaust gases back into the cylinders.
An EGR Valve is used in internal combustion engines to reduce Nitrogen Oxide by recirculating a portion of the exhaust gases back into the cylinders diluting the intake O2 reducing cylinder temperatures.
The EGR valve only opens at idle releasing the gasses to reduce the final emissions whilst waiting in traffic by lowering the volume of oxygen content entering the engine.
In basic terms, the EGR valve reduces the amount of oxygen entering the engine by replacing AIR with exhaust gas. It sounds good but it introduces lots of carbon to the inlet track.
The EGR system has a major downside, it allows carbon and oil (as part of the dirty exhaust gases) to be input into what should be the clean side of the engine. This means that everything after the EGR valve on the inlet side gets covered with oil, unburnt fuel and black carbon which over time builds up as carbon deposits and starts to cause a wide array of running issues.
For complete peace of mind we can remove the EGR completly from a vehicle, replace the compontents with blanking plates and modify the engine software through a retune to prevent any more EGR problems.
The EGR valve is the biggest cause of diesel engine problems all resulting from the coke and carbon it introduces to the clean induction side of the engine.
This is a very common procedure on all BMW models, we have a 100% sucess rate of curing all EGR problems on all BMW and Mini diesel engines.
Sometimes the engine ECU (Control Unit) will report error codes that point to the EGR valve directly. More often with vacumn based system the EGR valve will not throw an error and instead you will experience fault codes for the Air Mass / MAF Filter or if the fault has been present for a while, the worst cases may report a blocked DPF (Diesel Particulate Filter). In most cases we can check the live serial data from the engine ECU to check the amount of air flowing into the engine to determine if the Air Mass meter is working and if the EGR valve when operated changes the amount of air entering past the Air Mass Meter. Live data usually provides a good indication of what's going on.