Case IH 19900 (DTC 1A93) – Engine Controller / SCR Controller: High pressure intercooler outlet pressure sensor voltage higher than expected.

The engine control module is receiving a voltage signal from the intercooler outlet pressure sensor (boost pressure sensor) that exceeds the normal operating maximum. This typically indicates that the sensor's signal wire is shorted to a high voltage source, the sensor has lost its ground connection, or the sensor has failed internally.

• MAXXUM T4E
• 240 Series Axial-Flow Combines
• 7240
• 8240
• 9240

1. 1

   Connect the Case IH Electronic Service Tool (EST) to the diagnostic port to confirm DTC 1A93 (19900) is active in the Engine Controller.

2. 2

   Locate the intercooler outlet pressure sensor on the engine's intake/intercooler piping. Inspect the sensor connector for moisture, corrosion, or pushed-out pins.

3. 3

   Disconnect the sensor and use a digital multimeter to check the sensor ground circuit. An open ground will cause the signal voltage to read artificially high.

4. 4

   Check the signal wire for a short-to-power (shorted to a 5V reference or 12V source).

5. 5

   If the wiring harness, 5V reference, and ground circuits all test normal, the sensor itself is likely internally shorted and requires replacement.

1. 1

   Power down and disconnect battery

   Power down the machine, ensure the engine is cool, and disconnect the battery to prevent electrical spikes.

2. 2

   Locate sensor

   Locate the high-pressure intercooler outlet pressure sensor (boost pressure sensor).

3. 3

   Disconnect harness

   Depress the locking tab and disconnect the electrical harness from the sensor.

4. 4

   Repair wiring

   If wiring damage was identified during the diagnostic phase, repair the wiring harness or splice in a new connector pigtail.

5. 5

   Remove faulty sensor

   If the sensor is faulty, unthread/unbolt the old sensor from the intercooler outlet manifold.

6. 6

   Install new sensor

   Install the new replacement sensor and tighten it to the manufacturer's specified torque.

7. 7

   Reconnect harness

   Reconnect the electrical harness, ensuring it clicks securely into place.

8. 8

   Clear codes and verify

   Reconnect the battery, turn the ignition on, and use the EST to clear the fault codes from the Engine Controller. Run the engine to verify the code does not return and that boost pressure readings are within normal parameters.