Deutz-Fahr 126 – ECU: Timeout in CAN Reception Message from AMB; Ambient Temperature Sensor

The engine's Electronic Control Unit (ECU) has not received the expected data message from the ambient temperature sensor over the CAN bus within the specified timeframe. This timeout (associated with SPN 523603 and FMI 9 for Abnormal Update Rate) indicates the system is unable to receive or process the expected ambient temperature message, which can be caused by a failed sensor, damaged wiring, or a broader CAN network communication error.

• Series 8
• Series 7
• Series 6
• Series 6.4
• Series 5

1. 1

   Visually inspect the wiring harness connected to the ambient temperature sensor for chafing, cuts, or corrosion.

2. 2

   Check the connectors at the sensor and the ECU for bent, loose, or corroded pins.

3. 3

   Use a diagnostic tool to check for other active CAN bus-related fault codes that might indicate a wider network problem.

4. 4

   Perform a CAN bus resistance check with the ignition and battery master switch turned off and the battery disconnected. Measure between CAN High and CAN Low: a healthy bus should read approximately 60 Ohms, around 120 Ohms indicates a missing terminating resistor or open circuit, and significantly lower than 60 Ohms indicates a short circuit between the CAN lines.

5. 5

   Perform a continuity test on the wires between the ambient temperature sensor and the ECU, and check for shorts to power or ground.

6. 6

   Test the ambient temperature sensor's internal resistance against manufacturer specifications.

1. 1

   Repair wiring and connectors

   If any damaged wiring or connectors are found during inspection, repair or replace them. Ensure all connections are clean and secure.

2. 2

   Replace ambient temperature sensor

   If the wiring and CAN network test good, the ambient temperature sensor is the most likely cause. Replace the sensor with a new one.

3. 3

   Test or replace ECU

   If the fault persists after replacing the sensor and verifying the wiring, the issue could be with the ECU itself. Have a qualified technician test the ECU for internal faults.

4. 4

   Clear fault codes

   After performing repairs, clear the fault code using a diagnostic tool and run the vehicle to ensure the fault does not return.