The maximum temperature of the sensor at the bung (the sensor hexagon) should not exceed 500 oC or 900 oF. If these temperatures are exceeded in your application you should either install a copper heat sink (instructions below) or the Innovate Motorsports Heat-Sink Bung extender (HBX-1). The bung extender is recommended for situations where airflow is restricted or the encountered heat is higher than a heat sink can handle.