Case IH 19261 – Engine Control Module (ECM / ECU): Coolant pressure plausibility failure

The engine control system is receiving an analog signal from the coolant pressure sensor that does not make logical sense given the current operating state of the engine.

• Tier 4b
• Case IH Puma
• Case IH Optum
• Case IH Magnum
• Case IH Steiger
• Case construction equipment

1. 1

   Check for Sensor Drift: Using a diagnostic laptop (CNH EST or Iveco EASY), monitor the live data for the coolant pressure sensor while the engine is off and cold. If it reads anything other than ambient/zero pressure, the sensor has drifted and is defective.

2. 2

   Wiring and Connector Inspection: Inspect the wiring harness and the connector at the coolant pressure sensor. The ECU monitors the raw voltage of this sensor; look for corroded pins, an open circuit, or a short circuit to a voltage source/ground.

3. 3

   Verify Actual Coolant Pressure: Use a mechanical pressure gauge to verify the actual pressure in the cooling system. If the mechanical gauge shows abnormal pressure, the sensor is doing its job and you may have a mechanical issue (e.g., a failing water pump, a stuck thermostat, or a blown head gasket causing combustion pressure to enter the cooling system).

4. 4

   Check Related Systems: Ensure the coolant level is adequate and that there are no active faults for the Coolant Temperature Sensor or Coolant Level Sensor, which could skew the ECU's plausibility logic.

1. 1

   Prep the Machine

   Park the machine on a level surface, turn off the engine, and let it cool down completely to avoid burn hazards and to allow cooling system pressure to drop.

2. 2

   Relieve Pressure

   Slowly loosen the coolant reservoir cap to relieve any residual pressure in the cooling system, then retighten it.

3. 3

   Disconnect the Sensor

   Locate the coolant pressure sensor (typically located near the coolant reservoir or on the main coolant manifold, depending on the specific FPT engine layout) and disconnect its electrical harness.

4. 4

   Remove the Sensor

   Unthread the defective coolant pressure sensor. Have a rag ready to catch any minor coolant spillage.

5. 5

   Install the New Sensor

   Thread the new OEM coolant pressure sensor into place and tighten to the manufacturer's specified torque.

6. 6

   Reconnect and Test

   Reconnect the electrical harness. Top off the coolant if any was lost.

7. 7

   Clear Codes

   Start the engine, check for leaks around the new sensor, and use a diagnostic tool to clear the 19261 fault code.