Case IH 143 – Engine Control Unit (ECU) / Transmission Controller / Hydraulic EHR Controller: Engine Oil Pressure Low - Warning / System Pressure Transducer Circuit is Open

Fault Code 143 indicates the ECU has detected engine oil pressure below the safe warning limit, or a fault in the oil pressure sensor circuit. Note: The description 'System pressure transducer circuit is open' actually corresponds to Fault Code 2159 (loss of communication with the hydraulic system pressure transducer).

• STX Steiger
• MX Magnum Series (MX210, MX230, MX255, MX285)
• TG Series
• Steiger
• Puma (130-240)
• Maxxum (110-150)
• Magnum (250-380)

1. 1

   For Code 143: Verify Oil Level by checking the engine oil dipstick to ensure the crankcase has sufficient oil.

2. 2

   For Code 143: Plumb a manual/mechanical oil pressure gauge directly into the engine block to verify if the actual oil pressure is dangerously low, or if the sensor is lying to the computer.

3. 3

   For Code 143: Inspect the oil pressure sensor wiring harness and connector for damage, corrosion, or loose pins.

4. 4

   For Code 143: Check for related codes 135 (Voltage too high) or 141 (Voltage too low), which confirm an electrical circuit failure.

5. 5

   For Code 2159: Locate the system pressure transducer (often located on the remote valve block or powershift manifold).

6. 6

   For Code 2159: Ensure the connectors are fully seated, not damaged, and that the pins are in the correct position with a tight fit.

7. 7

   For Code 2159: Disconnect the sensor and use a multimeter to check for continuity between the sensor connector and the ECU pins.

1. 1

   Determine if issue is electrical

   For Code 143: If the mechanical gauge shows normal oil pressure while the fault is active, the issue is electrical.

2. 2

   Check wiring continuity

   For Code 143: Disconnect the oil pressure sensor and check the wiring harness for continuity back to the ECU.

3. 3

   Replace sensor

   For Code 143: If the wiring harness tests good (no shorts or opens), the oil pressure sensor has failed internally. Remove the old sensor and install a replacement.

4. 4

   Inspect mechanical components

   For Code 143: If the mechanical gauge shows actual low oil pressure, do not run the engine. Drop the oil pan and inspect the lubricating oil pump, suction tube, and oil pressure regulator for mechanical failure.

5. 5

   Disconnect power

   For Code 2159: Turn off the machine and disconnect the battery.

6. 6

   Repair wiring harness

   For Code 2159: If the continuity test reveals an open circuit in the harness, trace the wiring back to the ECU to find the break or chafed wire. Repair the wire or replace the harness section.

7. 7

   Relieve pressure

   For Code 2159: If the wiring harness has perfect continuity, the transducer itself has failed internally. Relieve hydraulic system pressure.

8. 8

   Replace transducer

   For Code 2159: Unthread the failed system pressure transducer and install the new one.

9. 9

   Verify repair

   For Code 2159: Reconnect the wiring harness, clear the fault codes using the Electronic Service Tool, and return the machine to proper operation to verify the fix.