Exhaust Gas Recirculation: Notes
The recycling of exhaust gases is one of the methods used to reduce NOx in a diesel engine. By introducing exhaust gas into the intake stream, the amount of oxygen in the combustion chamber is reduced which results in lower combustion chamber temperatures.
The EGR systems differ between the E70 and the E90. Both vehicles use the "high-pressure EGR", but the E70 uses an additional "low-pressure EGR" system. The low pressure EGR system is required in the E70 due to it's additional weight and higher operational loads (i.e. towing etc.).