Deutz-Fahr 1078 – ECM: EGR Differential Pressure Sensor Voltage Low

The Engine Control Module (ECM) has detected that the voltage from the Engine Differential Pressure Exhaust Gas Recirculation 1 sensor is below the normal operating range or is short-circuited to ground. This sensor measures the difference in exhaust gas pressure before and after a specific point in the EGR circuit to calculate the flow rate of recirculated exhaust gas. When this fault is active, the ECM will typically disable the EGR valve, causing it to remain closed, and trigger the amber CHECK ENGINE light.

• Agrotron 6120
• Agrotron 6130
• Agrotron 6140
• Agrotron 6145.4
• Agrotron 6155
• Agrotron 6155.4
• Agrotron 6165
• Agrotron 6165.4
• Agrotron 6175
• Agrotron 6175.4
• Agrotron 6185
• Agrotron 6205
• Agrotron 6215
• Agrotron 6120 TTV
• Agrotron 6130 TTV
• Agrotron 6140 TTV
• Agrotron 6155 TTV
• Agrotron 6155.4 TTV
• Agrotron 6165 TTV
• Agrotron 6165.4 TTV
• Agrotron 6175 TTV
• Agrotron 6175.4 TTV
• Agrotron 6185 TTV
• Agrotron 6205 TTV
• Agrotron 6215 TTV
• Agrotron 7230 TTV
• Agrotron 7250 TTV
• Agrotron 8280 TTV
• Agrotron 9270 TTV
• Agrotron 9290 TTV
• Agrotron 9310 TTV
• Agrotron 9340 TTV

1. 1

   Verify ECM Calibration: Ensure the ECM software is up to date, as an outdated calibration can sometimes cause erroneous fault codes.

2. 2

   Visual Inspection: Thoroughly inspect the EGR differential pressure sensor, its electrical connector, and the associated wiring harness for melted or chafed wires (especially near hot exhaust components), moisture, or corrosion.

3. 3

   Inspect Sensor Hoses: Check the two hoses connected to the sensor for any cracks, melting, or blockages.

4. 4

   Check for Short to Ground (Wiring Cause): Disconnect the sensor's electrical connector. With the keyswitch on, use a multimeter to check for continuity between the signal wire pin on the harness side and a known good ground. A short here indicates a wiring harness fault.

5. 5

   Verify Supply Voltage: At the harness connector for the sensor, measure the voltage between the 5-volt supply pin and the ground/return pin. It should read approximately 5 volts. If not, the issue may be the ECM or the wiring harness.

6. 6

   Test the Sensor (Internal Short Cause): If the harness tests correctly, reconnect the sensor. If the signal voltage drops to near zero upon reconnection, the sensor has an internal short to ground and is faulty.

1. 1

   Isolate and disconnect power

   Turn the vehicle's ignition and master disconnect switch to the OFF position before beginning any repairs.

2. 2

   Locate the sensor

   Find the EGR differential pressure sensor, which is typically mounted on the engine or firewall away from direct exhaust heat, connected to the EGR piping via two hoses.

3. 3

   Address wiring or hose issues

   If diagnostic checks revealed a short in the harness, repair the damaged section of wire. If hoses are blocked or damaged, clear or replace them.

4. 4

   Replace the sensor

   If the sensor has an internal short, disconnect the electrical connector. Carefully loosen the clamps and remove the two pressure hoses, noting their original positions. Remove the mounting bolts, install the new sensor securely, reconnect the pressure hoses to their correct ports, tighten the clamps, and reconnect the electrical connector.

5. 5

   Clear fault codes

   Reconnect the battery, turn the ignition on, and use a diagnostic tool to clear fault code 1078 (SPN 411 FMI 4).

6. 6

   Verify the repair

   Start the engine and let it run to ensure the CHECK ENGINE light does not reappear. It may be necessary to perform a DPF regeneration or operate the machine under load to fully validate the repair.