Case IH 456 – Engine Controller (ENG): Fuel Pressure in pump is not changing with operating conditions.

This code indicates that the fuel pressure reading is stuck in a specific range or is reading erratically. It points to a fuel starvation issue or a failure in the fuel pressure sensor circuit.

• MX Magnum
• STX Steiger
• MX240
• MX270
• MX285
• Axial-Flow 2388
• 2577
• FLX3510
• Patriot 4420

1. 1

   Check inline fuel filters for clogging or high fuel intake restriction

2. 2

   Check the fuel system for air intrusion

3. 3

   Verify that the fuel lift pump is operating correctly

4. 4

   Inspect the harness pigtail and connector pins on the fuel pressure sensor for damage, corrosion, or a circuit fault

5. 5

   Check if code 456 is accompanied by other CAPS pump codes, such as 277 (Injection control valve failed) or 329 (Over pumping)

1. 1

   Replace Fuel Filters

   Start by changing the fuel filters to eliminate fuel starvation caused by restriction, then re-prime the tractor.

2. 2

   Repair Wiring

   If the harness pigtail or connector pins at the fuel pressure sensor are damaged, repair or replace the wiring.

3. 3

   Replace Fuel Pressure Sensor

   If the wiring is intact but the pressure reading remains erratic or stuck, replace the fuel pressure sensor/switches.

4. 4

   CAPS Pump Repair/Replacement

   If the sensor and fuel supply are good, but the tractor continues to lose power and throw code 456 (especially alongside codes 277 or 329), the CAPS pump is likely failing. You will need to either replace the injection control valve module on the pump, remove the entire CAPS pump and send it to a diesel shop for a rebuild, install a rebuilt CAPS pump, or perform a P-pump conversion.