Theory of Operation

WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The Diesel Exhaust Fluid (DEF) Tank Level Sensor and Diesel Exhaust Fluid (DEF) Tank Temperature Sensor are a combination sensor used to measure the level and temperature of the fluid in the DEF Tank. Though combined, the level sensor and the temperature sensor operate independent of each other. Both sensors operate as a two wire 5-Volt sensor. The DEF Tank Level Sensor is a 14 point magnetic reed switch sensor. The DEF Tank Temperature Sensor is a negative temperature coefficient sensor. The DEF Dosing Control Unit will illuminate the MIL lamp via the Powertrain Control Module (PCM) immediately after this diagnostic runs and fails. The DEF Dosing Control Unit will turn off the MIL lamp via the PCM immediately after the diagnostic runs and passes in three consecutive key cycles.