Case IH 3109 – VCM / EDC / ECU: Boost Pressure Sensor (downstream) CAN signal is invalid.

The control module is receiving a signal over the Controller Area Network (CAN) bus from the downstream boost pressure sensor that is corrupted, missing, or out of expected parameters, which can affect fuel metering and emissions controls.

• CNH Industrial equipment equipped with Tier 4 Final engines
• Case IH tractors
• Case IH combines
• Case Construction N-Series Tractor Loader Backhoes

1. 1

   Check for accompanying codes that might point to a specific electrical failure, such as 3115, 3116, 3103, or 3094

2. 2

   Inspect the CAN bus wiring harness and the connector at the downstream boost pressure sensor for opens, shorts, chafing, or corrosion

3. 3

   Disconnect the sensor and use a multimeter to verify that the sensor is receiving the correct reference voltage and has a solid ground

4. 4

   Verify the continuity of the CAN High and CAN Low communication lines between the sensor connector and the VCM/ECU

1. 1

   Locate the Sensor

   Find the downstream boost pressure sensor, which is typically mounted on the intake manifold or on the piping immediately downstream of the charge air cooler.

2. 2

   Inspect and Clean

   Disconnect the sensor harness. Clean the connector pins with electrical contact cleaner and ensure no pins are pushed back or bent.

3. 3

   Repair Wiring

   If the diagnostic checks revealed a short or open circuit in the harness, repair the damaged section of the wiring or replace the pigtail connector.

4. 4

   Replace the Sensor

   If the wiring, power, ground, and CAN lines test good but the code persists, the internal circuitry of the sensor has failed. Remove the retaining bolt(s), pull the old sensor out, and install the new sensor. Ensure the rubber O-ring/seal is seated properly to prevent boost leaks.

5. 5

   Clear and Verify

   Reconnect the harness, use a diagnostic scan tool to clear the VCM/ECU fault codes, and run the engine under load to verify the code does not return.