New Holland 3805 – ECU: Rail pressure sensor : maximum rail pressure exceeded

The fuel pressure within the common rail has surpassed the maximum allowable safety limit. The system may also log a secondary condition stating that the rail pressure reduction by blank shots during after run (BSA) was aborted, meaning the system attempted to reduce the excessive pressure but was unable to do so successfully.

• T6 series
• T6.120
• T6.175
• T6000 series
• T7 series
• T7.170
• T7.250
• T8 series
• T8020
• T8030
• T8040
• CR series
• CR7.80
• CR8.90
• CR9.90
• WE210B

1. 1

   Check the sensor signal circuit voltage (the ECU triggers this fault if voltage is greater than 4.9 V for more than 0.2 seconds).

2. 2

   Inspect the wiring harness and connectors for the rail pressure sensor for damaged insulation, corrosion, or a short circuit to the battery or ground.

3. 3

   Verify that the fuel metering unit or Pressure Relief Valve (PRV) is not mechanically stuck closed, which would cause an actual over-pressurization event rather than a sensor reading error.

1. 1

   Depressurize fuel system

   Turn off the machine, remove the key, and disconnect the battery. Warning: High-pressure fuel systems can be dangerous; ensure the engine has been off long enough for the fuel rail pressure to bleed down before loosening any fittings.

2. 2

   Locate the sensor

   Find the fuel rail pressure sensor, which is threaded directly into the common fuel rail.

3. 3

   Perform electrical testing

   Disconnect the electrical connector. Use a multimeter to test the reference voltage and ground at the harness connector to rule out a wiring issue.

4. 4

   Remove the faulty sensor

   If the wiring is intact and the voltage is out of range, the sensor is likely faulty. Carefully unscrew the old rail pressure sensor from the fuel rail.

5. 5

   Install the new sensor

   Thread the new OEM rail pressure sensor into the rail and torque it to the manufacturer's specifications.

6. 6

   Reassemble components

   Reconnect the electrical harness securely to the new sensor.

7. 7

   Clear codes and test

   Reconnect the battery. Use a diagnostic tool (such as the CNH E.A.S.Y. system) to clear the 3805 fault code. Start the engine and monitor the live rail pressure data to ensure it remains within normal operating limits and the code does not return.