DTC P0405 Or DTC P0406: Description
WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.
The EGR temperature sensor detects temperature changes in the EGR passageway. When the EGR valve opens, hot exhaust gases flow, and the temperature in the passageway changes. The EGR temperature sensor is a thermistor that modifies a voltage signal sent from the ECM. This modified signal then returns to the ECM as an input signal. As the temperature increases, EGR temperature sensor resistance decreases. This sensor is not used to control the engine system. It is only used for on-board diagnosis.