Deutz-Fahr 411 – ECU: Defective Ambient Air Pressure Signal from CAN Bus

The Engine Control Unit (ECU) has detected a defective ambient air pressure signal from the CAN bus. This indicates the signal is lost, out of expected range, or implausible compared to other sensor readings. The ECU relies on this atmospheric pressure data to calculate the correct air-fuel mixture, control turbocharger boost, and adjust engine timing. When this fault is active, the engine may enter a derated or limp-home mode to prevent damage.

• Deutz TCD 2.9
• Deutz TCD 3.6
• Deutz TCD 4.1
• Deutz TCD 6.1 L6
• Deutz 2012 Series
• Deutz 2013 Series
• Machines with EMR3 control systems
• Machines with EMR4 control systems
• Genie equipment
• BOMAG equipment

1. 1

   Visually inspect the ambient air pressure sensor wiring harness and ECU connectors for chafing, cuts, pinched wires, heat damage, corrosion, or bent pins.

2. 2

   Verify the sensor's power supply (approximately 5 volts) and ground circuit using a multimeter with the ignition on (for external sensors).

3. 3

   Check the signal voltage with the ignition on and engine off; it should correspond to local atmospheric pressure and not be stuck at 0V or 5V.

4. 4

   Compare the ambient pressure sensor reading with the charge air pressure (boost) sensor reading at ignition on/engine off using a scan tool (values should be nearly identical to rule out implausibility).

1. 1

   Confirm fault codes

   Use a diagnostic scan tool to confirm fault code 411 (or SPN 108) is active. Note any other active codes that might indicate shared wiring issues.

2. 2

   Repair wiring or connectors

   If diagnostic checks reveal damaged wiring, poor grounds, or a faulty power supply, repair or replace the affected harness section and ensure all connections are clean and secure.

3. 3

   Replace ambient air pressure sensor

   If the sensor is external and all wiring, power, and ground checks pass, replace the ambient air pressure sensor.

4. 4

   Replace ECU (if integrated)

   If the ambient pressure sensor is integrated directly into the ECU (common on some EMR3/EMR4 units) and external wiring issues are ruled out, the ECU must be replaced.

5. 5

   Clear codes and verify

   Clear all fault codes with a scan tool. Perform a key cycle (ignition off until ECU powers down completely, then on), start the engine, idle for at least one minute, and verify the code does not return.