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 X5 and the 335d. Both vehicles use the "High-pressure EGR", but the X5 uses an additional "Low-pressure EGR system. The low pressure EGR system is required in the X5 due to it's additional weight and higher operational loads (i.e. towing etc.).