EGTS are used to monitor the optimum operating point, to protect the relevant components from temperature overload and to keep them in the desired temperature range for optimal conversion rates. EGTS are therefore an important component for the reduction of harmful emissions from vehicles. EGTS serve as a temperature monitor for turbochargers, catalytic converters, diesel particle filters and nitrogen oxide reduction systems. There are two types of EGTS: Positive Temperature Coefficient (PTC) and Negative Temperature Coefficient (NTC). Resistance in PTC sensors increases with rising temperature, while with NTC sensors, resistance decreases with increasing temperature.