Description - Diesel Exhaust Fluid Tank Level Sensor: Operation

WARNING: This page is about a different variant/trim than selected.

The Diesel Exhaust Fluid (DEF) tank level sensor and Diesel Exhaust Fluid (DEF) tank temperature sensor are a combined 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 three wire 12-Volt sensor.

A DEF level sensor integrated into the supply pump module sends the Powertrain Control Module (PCM) a Pulse Width Modulated (PWM) signal to indicate the fluid level and temperature in the tank. The level sensor has no moving parts and uses ultrasonic waves to measure the fluid level within the tank. The sensor has a measurement range of 15 to 400 mm above the sensor surface.

The DEF tank temperature sensor provides the PCM with a PWM signal indicating the temperature of the DEF in the tank. This sensor is used to determine when activation of the integral tank heater is required to thaw the DEF within the tank. The temperature sensor has a measurement range of -40C (-40F) to 80C (176F). The PWM signal is linear within that range; therefore, a 100% signal is equal to 80C (176F) and a 0% signal is equal to -40C (-40F).