John Deere 003031.04 – DCU: DEF Tank Temp Sensor Voltage Low

The voltage from the Diesel Exhaust Fluid (DEF) tank temperature sensor is lower than the expected range. This condition typically points to an internal short circuit within the DEF header assembly. An abnormally low voltage prevents the accurate monitoring of the DEF tank's temperature, which is crucial for the proper functioning of the Selective Catalytic Reduction (SCR) system.

• 330G
• 331G
• 332G
• 333G
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R

1. 1

   Use a diagnostic scanner to confirm that 003031.04 is the active or stored fault code in the Dosing Control Unit (DCU)

2. 2

   Check for intermittent issues using the vehicle's technical manual procedures for diagnosing intermittent DTCs

3. 3

   Inspect the wiring harness connected to the DEF tank header assembly (identified as the Left Main Harness W3 on some models) for visible signs of damage, corrosion on the connectors, or loose connections

4. 4

   Note that if wiring appears intact, external testing of the sensor's circuit may not be sufficient, as the primary cause is usually an internal short circuit within the DEF header itself

1. 1

   Relieve system pressure

   If applicable, relieve any pressure in the DEF system before disconnecting any lines.

2. 2

   Disconnect lines and connectors

   Carefully disconnect the electrical connector and the DEF lines from the DEF tank header assembly.

3. 3

   Remove old header

   Unbolt and remove the DEF tank header assembly from the DEF tank.

4. 4

   Install new header

   Install the new, genuine John Deere DEF tank header assembly, ensuring it is seated correctly.

5. 5

   Reconnect lines

   Reconnect the electrical connector and the DEF fluid lines to the new header assembly.

6. 6

   Clear fault codes

   Use a diagnostic tool to clear the 003031.04 fault code from the Dosing Control Unit.

7. 7

   Verify repair

   Start the machine and let it run to confirm that the fault code does not reappear and that the DEF system is functioning correctly.