Case IH 3425 (DTC 1438) - ECU – Engine ECU: Under boost failure

This code indicates that the engine's boost pressure is lower than expected. The Electronic Control Unit (ECU) logs this fault if it determines that the actual boost pressure is lower than the target pressure, which is calculated based on current engine speed and ambient pressure.

• MAXXUM T4E
• Case IH Puma Series Tractors
• Case IH Magnum Series Tractors (e.g., 235–340 Series 4)
• Case IH 240 Series Axial-Flow Combines (7240, 8240, 9240)

1. 1

   Verify that the machine is not simply being operated in extreme environmental ambient pressures (e.g., extreme high altitudes), which can naturally cause lower-than-expected boost.

2. 2

   Check for a restricted or heavily soiled engine air filter.

3. 3

   Inspect all charge-air cooler (CAC) piping, hoses, and clamps between the turbocharger and the intake manifold for splits, blow-offs, or loose connections.

4. 4

   If equipped with an EVGT, visually inspect the actuation mechanism to verify the linkage is properly attached and not restricted, sticking, or blocked.

5. 5

   If equipped with a standard wastegate, visually inspect the wastegate linkage to ensure it is not damaged or disconnected.

1. 1

   Resolve Air/Boost Leaks

   Replace any clogged air filters. Reconnect or replace any damaged intake hoses or loose clamps found during the diagnostic checks.

2. 2

   Free up Turbo Linkage

   If the EVGT actuator or wastegate linkage is sticking, attempt to free the linkage. If the actuator has failed or the linkage is broken, the actuator or turbocharger assembly may need to be replaced.

3. 3

   Test/Replace the Sensor

   Inspect the wiring harness for chafing or shorts to a low source. If the wiring is intact, replace the intake boost pressure sensor (B-013).

4. 4

   Reset the Inducement System

   On emissions-regulated machines, if this fault is detected 3 times within 40 hours, the engine inducement system will lock. To clear this, the system must be reset using the dealer service tool (EST) by navigating to the 'Engine Restart Counter Reset' screen.