The Exhaust Gas Temperature (EGT) sensor protects the catalytic converter (TWC) from high temperatures. It turns the temperature into a voltage signal via an internal heat-sensitive resistor. This signal is sent to the Powertrain Control Module (PCM). On the other hand, in vehicles with diesel engines, this sensor determines the DEF (Diesel Exhaust Fluid) injection timing as temperatures rise. The resistance of the sensor varies according to the exhaust temperature, the higher the temperature, the lower the resistance voltage will be. In contrast, when the temperature is low, the voltage level will increase.
The fault code P242A OBDII is stored when the PCM detects a general malfunction in the EGT sensor circuit. This code may be accompanied by another code referring to the sensor.