Case IH 3898 – Engine Control Unit (ECU) / EDC: EGR Cooler: Temperature deviation of intake air after EGR.

This code indicates that the temperature of the intake air, measured after it has mixed with the recirculated exhaust gases from the EGR cooler, is outside the expected parameters. This typically means the EGR cooler is not cooling the exhaust gases sufficiently (often due to soot blockage or coolant flow issues), or the sensor measuring the temperature is providing inaccurate data.

• Farmall 115A
• Farmall 115U
• Steiger
• Magnum
• Maxxum
• Axial-Flow
• TR270B

1. 1

   Sensor Verification: Check the Intake Manifold Temperature and Pressure Sensor (MAP/IAT sensor). Use a diagnostic tool (like CNH EST) to monitor live data. If the temperature reads implausibly high or low when the engine is cold, the sensor is likely faulty.

2. 2

   Visual Inspection of Sensor: Remove the IAT sensor from the intake manifold. Check for heavy soot or carbon buildup that could insulate the sensor and cause delayed or inaccurate readings.

3. 3

   Coolant System Check: Verify the engine coolant level is full and that there are no air pockets in the cooling system. Ensure the coolant lines running to the EGR cooler are not pinched or restricted.

4. 4

   EGR Valve Operation: Ensure the EGR valve is not stuck open, which would allow excessive hot exhaust gas into the intake, overwhelming the cooler.

5. 5

   Wiring Harness: Inspect the pigtail connector and wiring harness leading to the IAT sensor for chafing, corrosion, or short circuits.

1. 1

   Turn off machine and disconnect battery

   If replacing the IAT Sensor: Turn off the machine and disconnect the battery.

2. 2

   Locate MAP/IAT sensor

   Locate the MAP/IAT sensor on the intake manifold.

3. 3

   Disconnect harness

   Disconnect the electrical harness connector.

4. 4

   Remove sensor

   Unbolt/unscrew the sensor and remove it.

5. 5

   Install new sensor

   Install the new sensor, ensuring the O-ring is seated properly to prevent boost leaks.

6. 6

   Reconnect and clear codes

   Reconnect the harness, reconnect the battery, and clear the fault codes.

7. 7

   Drain engine coolant

   If replacing the EGR Cooler: Wait for the engine to cool completely. Drain the engine coolant into a clean drain pan.

8. 8

   Remove intake piping and heat shields

   Remove the air intake piping and any exhaust heat shields obstructing access to the EGR cooler.

9. 9

   Disconnect coolant lines

   Disconnect the EGR cooler coolant lines.

10. 10

    Unbolt EGR cooler

    Unbolt the EGR cooler from the exhaust manifold and the EGR valve assembly.

11. 11

    Remove and inspect EGR cooler

    Remove the EGR cooler. Inspect the internal passages—if they are completely caked with hard soot, the cooler has failed.

12. 12

    Clean mating surfaces

    Clean the mating surfaces on the exhaust manifold and EGR valve.

13. 13

    Install new EGR cooler

    Install the new EGR cooler using new gaskets (never reuse old EGR gaskets as they will leak exhaust gas).

14. 14

    Reconnect lines and piping

    Reconnect the coolant lines and intake/exhaust piping.

15. 15

    Refill coolant and bleed air

    Refill the engine coolant. Start the engine and let it idle with the radiator cap off to bleed any air from the cooling system.

16. 16

    Clear codes and test run

    Connect a diagnostic tool, clear fault code 3898, and perform a test run under load to ensure the intake air temperature remains within the specified deviation limits.