Exhaust Temperature Sensor: Description and Operation

Purpose
The sensor signals the ECM and illuminates a warning lamp when catalyst temperatures exceed 95°C (203-221°F).
This prevents damage, to the catalytic converter and its surrounding area, from excessive heat.

Operation
Sensor is an "ON / OFF" switch that turns a warning light "ON", when heated to the specified temperature, and signals the ECM. The ECM deactivates the air pump's magnetic clutch which stops air injection into the converter.