Case IH 19151 – ECM: Missing DEF Quality Sensor CAN Frame

This fault code indicates a loss of CAN bus communication between the DEF Quality Sensor (integrated into the DEF tank header) and the engine's control system. Specifically, the system is missing the CRI1 (Catalyst Reagent Information 1) CAN frame, which transmits critical information regarding the DEF fluid's concentration, temperature, and tank level.

• Tier 4b
• Magnum
• Puma
• Maxxum
• Optum
• Steiger
• Quadtrac
• Axial-Flow 5130
• Axial-Flow 7130

1. 1

   Visually inspect the DEF Quality Sensor (DEF Header) electrical connector and wiring harness for chafing, breaks, or bent pins.

2. 2

   Disconnect the plug and check for white crystalline buildup or green copper corrosion caused by ammonia gas venting.

3. 3

   Verify that the DEF Quality Sensor is receiving proper voltage and has a solid ground connection.

4. 4

   Measure the resistance across the CAN High and CAN Low pins at the sensor connector. A healthy CAN bus should read approximately 60 ohms. If wiring is intact and power/ground are present, the internal circuitry of the DEF Quality Sensor has likely failed.

1. 1

   Disconnect power

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Clean work area

   Clean the area around the top of the DEF tank thoroughly to prevent dirt from falling into the tank.

3. 3

   Disconnect harness and lines

   Disconnect the electrical harness from the DEF Quality Sensor and the DEF fluid lines from the header using appropriate quick-disconnect tools. Clean any spilled DEF immediately with warm water, as it is highly corrosive when it crystallizes.

4. 4

   Remove old sensor

   Unscrew or unbolt the retaining ring/flange holding the DEF Header assembly to the tank, then carefully pull the old DEF Quality Sensor/Header assembly straight up and out of the tank.

5. 5

   Install new sensor

   Insert the new DEF Quality Sensor assembly, ensuring the rubber sealing gasket is properly seated to prevent leaks, and secure the retaining ring/flange.

6. 6

   Reconnect and clear codes

   Reconnect the DEF fluid lines and the electrical connector. Reconnect the battery, turn the ignition on, and use a diagnostic scan tool to clear the 19151 fault code.