Deutz-Fahr 137 – EMR4 ECU: Downstream NOx Sensor CAN Timeout

A timeout has occurred during the reception of the CAN message AT 1OG 1. The Engine Control Unit (EMR4) expects a continuous stream of data from the downstream NOx sensor over the CAN bus to verify SCR system efficiency. When this data stream is interrupted or not received within a specific timeframe, a timeout error is logged. This issue affects communication between systems and can potentially impact the performance of the NOx sensor in the SCR system and the DPF system after the catalyst.

• TCD 2013
• TCD 2015
• TCD 4.1
• TCD 2016
• TCD 2020
• TCD 2021

1. 1

   Visually inspect the wiring harness and connectors between the EMR4 ECU and the downstream NOx sensor for chafing, corrosion, pinched wires, or loose connections

2. 2

   Disconnect and reconnect the NOx sensor connector to ensure a secure and clean connection, checking for any bent or corroded pins inside

3. 3

   Verify the integrity of the CAN bus communication lines to the sensor, as a failure of the CAN bus message is a primary reason for this error

1. 1

   Confirm the fault

   Use a diagnostic tool to confirm that fault code 137 (SPN 3234, FMI 9) is active or stored in the EMR4 ECU.

2. 2

   Repair wiring or connectors

   If any damage to the wiring harness or connectors is found during the visual inspection, repair or replace the affected section to restore CAN communication.

3. 3

   Replace the NOx sensor

   If the wiring and connections are in good condition, the fault is likely an internal electronics failure within the NOx sensor itself. Replace the downstream NOx sensor located in the exhaust system after the SCR catalyst.

4. 4

   Clear fault codes

   After repairing the wiring or replacing the sensor, use a diagnostic tool to clear the fault codes from the ECU.

5. 5

   Verify the repair

   Start the engine and allow it to run under normal load or perform a test drive to confirm that the fault code does not reappear.