JCB 0x3D – ECU: Erroneous Signal for Barometric Pressure

The system has detected an incorrect or unreliable signal from the barometric pressure sensor. This can manifest as a CAN bus message error for the environmental pressure reading from the Engine Control Unit (ECU). The machine's typical reaction to this fault is a reduction in engine torque.

• Tracked and Wheeled Excavators (JS Series)
• Wheeled Loaders
• Telescopic Handlers
• Mini Excavators

1. 1

   Record and clear the code using a diagnostic tool to determine if the fault is persistent or intermittent

2. 2

   Verify the machine's battery voltage, as low voltage can cause electronic communication errors

3. 3

   Inspect the barometric pressure sensor wiring harness for rubbing, fraying, or melted insulation

4. 4

   Disconnect the sensor's electrical connector and check for corrosion (green deposits), bent pins, or moisture ingress

5. 5

   Ensure all machine earth/ground connections are clean, tight, and free from corrosion

1. 1

   Clean and secure connectors

   Clean the sensor's electrical connectors to remove any corrosion or debris, and ensure they are securely reconnected. Many intermittent faults are resolved this way.

2. 2

   Repair wiring harness

   If any damage is found on the wiring harness or connectors, repair or replace the affected sections. Ensure all connections are properly sealed against moisture.

3. 3

   Test sensor and circuit

   Use a multimeter to test the sensor's resistance (Ohms) and the expected voltage output from the ECU. Compare the readings against the official JCB service manual specifications.

4. 4

   Replace barometric pressure sensor

   If the sensor fails multimeter testing or if all wiring and voltage checks pass but the fault persists, replace the barometric pressure sensor.

5. 5

   Verify repair

   Clear the fault codes and operate the machine to ensure the code does not reappear and engine torque is restored.