Case IH 19705 – Engine Control Unit (ECU): Failure to maintain minimum common rail pressure

The actual fuel pressure measured in the common rail is deviating significantly from the target pressure requested by the engine control unit. The system detects that the positive control deviation has exceeded the maximum allowable limit while the fuel metering unit is operating, often triggered when the system suspects a low fuel tank condition is causing fuel flow disruptions.

• Tier 4b
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 130
• Maxxum 140
• Maxxum 145
• Maxxum 150
• Puma 115
• Puma 125
• Puma 130
• Puma 140
• Puma 145
• Puma 150
• Puma 155
• Puma 160
• Puma 165
• Puma 170
• Puma 175
• Puma 180
• Puma 185
• Puma 195
• Puma 200
• Puma 210
• Puma 215
• Puma 220
• Puma 225
• Puma 230
• Puma 240
• Optum 250
• Optum 270
• Optum 300
• Vestrum 100
• Vestrum 110
• Vestrum 120
• Vestrum 130
• Farmall 90C
• Farmall 95A
• Farmall 100C
• Farmall 105A
• Farmall 110C
• Farmall 110U
• Farmall 115A
• Farmall 120C
• Farmall 120U
• Magnum 245-335
• Steiger 280-335

1. 1

   Verify the fuel level in the tank, as drawing air from an empty or near-empty tank directly triggers this deviation logic

2. 2

   Check for external fuel leakage in both the high-pressure and low-pressure fuel circuits

3. 3

   Check for bends, crimps, or restrictions in the fuel suction lines

4. 4

   Inspect the primary fuel filter and the pre-filter (baby filter) for choking, clogging, or water contamination

5. 5

   Check for excessive fuel leakage from the rail return line while the engine is in a running condition

1. 1

   Address Fuel Supply

   Ensure the fuel tank has adequate clean fuel. If the tank was run low, bleed the air from the fuel lines.

2. 2

   Clear Restrictions

   Straighten any crimped low-pressure suction lines.

3. 3

   Replace Filters

   Clean the pre-filter and replace the main fuel filter element to rule out flow restrictions.

4. 4

   Test the Pressure Relief Valve (PRV)

   If the fault persists, the mechanical pressure relief valve on the fuel rail may be popping off prematurely or leaking. Replace if it fails to hold target pressure.

5. 5

   Test the Fuel Rail Pressure Sensor

   Verify the sensor's voltage output is within the standard range. If it is sending erratic raw values to the ECU, replace the sensor.

6. 6

   Injector Leak-Off Test

   Remove the injector return lines and measure the return flow. An injector nozzle plunger stuck in the open position will cause a massive pressure drop, leading to this code. Replace any faulty injectors.

7. 7

   High-Pressure Pump Test

   If all lines, filters, sensors, and injectors pass, remove the high-pressure fuel pump (and its metering unit/fuel quantity control valve) and have it tested by an authorized dealer for internal failure.

8. 8

   Clear Codes

   Use a diagnostic scan tool to clear the 19705/19715 codes and test run the machine under load to verify the repair.