Case IH 3631 – Engine Control Unit (ECU): Fuel in Oil sensor plausibility

The crankcase differential pressure sensor registered a value greater than 5 kPa (0.7 psi) after the ECU started up. This indicates suspected fuel leaking into and diluting the engine oil, which increases the overall fluid level in the oil pan and subsequently increases crankcase pressure.

• Steiger 350
• Steiger 400
• Steiger 425
• Steiger 450
• Steiger 500
• Steiger 540
• Steiger 550
• Steiger 600
• Quadtrac Tractors
• Rowtrac Tractors
• Combine 5140
• Combine 6140
• Combine 7140
• Combine 7240
• Combine 8240
• Combine 9240
• Wheel Loader 1021G
• Wheel Loader 1121F
• Wheel Loader 1121G

1. 1

   Check the engine oil level on the dipstick to verify if it is overfull.

2. 2

   If the oil level is overfull (indicating potential fuel dilution), perform a fuel pressure test to inspect the engine's internal fuel system for leaks.

3. 3

   Check the wiring harness and electrical connections leading to the crankcase pressure sensor for any shorts, breaks, or corrosion.

1. 1

   Repair fuel leak and change oil

   If diagnostic checks reveal an overfull oil pan due to fuel dilution, locate and repair the internal fuel system leak. Then, completely drain and replace the engine oil and filter.

2. 2

   Repair sensor wiring

   If the oil level is normal, inspect the wiring harness connected to the crankcase pressure sensor. Repair any defects found in the wiring or connections and cycle the key to check if the fault has been corrected.

3. 3

   Replace crankcase pressure sensor

   If no defects are found in the wiring or connections and the oil is not diluted, the sensor itself has failed. Remove the defective crankcase pressure sensor and install a replacement.

4. 4

   Clear fault codes

   Clear the fault codes using an Electronic Service Tool (EST) or by navigating the machine's diagnostic display.