Deutz-Fahr SPN 3480 FMI 4 – ACM (Aftertreatment Control Module): SCR Catalyst Temperature Sensor: Signal voltage too low

The signal voltage from the temperature sensor has dropped below the normal operating range. This is typically caused by a short circuit to ground in the sensor's wiring harness, a damaged connector, or an internal failure of the sensor itself.

• Deutz-Fahr Agrotron Series
• Deutz-Fahr Serie 6
• Deutz-Fahr Serie 9

1. 1

   Disconnect the SCR temperature sensor and inspect the connector for damaged, corroded, or bent pins.

2. 2

   Inspect the SCR temperature sensor body for physical cracks or damage, and check the mounting threads for damage or exhaust leaks.

3. 3

   Trace the wiring harness from the sensor back to the ACM, looking for chafed wires rubbing against the chassis or exhaust components that could cause a short to ground.

1. 1

   Safety Prep

   Shut off the engine, apply the parking brake, and chock the wheels.

2. 2

   Disconnect Power

   Disconnect the machine's batteries to prevent electrical shock or shorting, as the magnetic switch studs remain at battery voltage.

3. 3

   Gain Access

   If necessary, remove the side fairing or exhaust heat shields to access the Aftertreatment Device (ATD).

4. 4

   Disconnect Wiring

   Disconnect the electrical connection from the SCR temperature sensor.

5. 5

   Free the Harness

   Cut and remove any zip ties securing the sensor's wiring harness to the ATD or mounting brackets.

6. 6

   Remove Sensor

   Using a specialized sensor socket tool, carefully unscrew and remove the SCR temperature sensor from the ATD.

7. 7

   Install New Sensor

   Thread the new sensor into the ATD by hand to prevent cross-threading, then tighten to the specified OEM torque.

8. 8

   Reassembly

   Reconnect the electrical harness, secure it with new high-temperature zip ties, reinstall any fairings, and reconnect the batteries. Clear the fault codes using a diagnostic tool.