The sensor referenced below appears to be between the DOC and the SCR. Turbo -> DOC -> SCR -> DPF. This sensor is between the DOC and SCR just prior to the urea injector.
Exhaust Gas Temperature Sensor Circuit Low Bank 1 Sensor 2
Description: The powertrain control module (PCM) monitors the exhaust gas temperature (EGT) sensor for a low voltage concern. The test fails when the sensor voltage is less than 0.10 volt for more than 15 seconds.
EGT12 signal circuit short to SIGRTN
EGT12 signal circuit short to ground
Damaged EGT12 sensor
Diagnostic Aids The presence of this DTC may indicate that the vehicle is operating in derate mode and may experience a loss of power.
An EGT12_V PID value less than 0.10 volt indicates a concern.