Case IH 3458 – Engine Control Module (ECM / ECU): Crankcase pressure too high

This Diagnostic Fault Code (DFC) indicates that the engine's crankcase pressure (blow-by pressure) has exceeded the maximum allowable threshold. High crankcase pressure is typically caused by a restricted crankcase ventilation system, overfilled engine oil, a faulty sensor, or excessive internal engine wear (blow-by).

• Case IH 240 Series Combines (6140, 7140, 7240, 8240, 9240)
• Case IH Steiger & Quadtrac Tractors (350, 380, 400, 450, 500, 600)
• Case IH Maxxum and Puma Tractors
• Case Construction N-Series Loaders (580N, 590SN)

1. 1

   Check Engine Oil Level: Verify that the engine oil is not overfilled. Fuel dilution (fuel in the oil) or simply overfilling the oil can reduce crankcase volume and artificially spike crankcase pressure.

2. 2

   Inspect the Crankcase Breather Filter: A clogged or severely restricted blow-by/crankcase ventilation filter is the most common cause of this code.

3. 3

   Test the Crankcase Pressure Sensor: Check the sensor and its wiring harness for damage, corrosion, or shorts. A failing sensor can send a false high pressure signal to the ECU.

4. 4

   Check for Mechanical Blow-By: If the filter and sensor are functioning properly, the engine may have excessive mechanical blow-by caused by worn piston rings, scored cylinder liners, or a failed turbocharger seal pressurizing the crankcase.

1. 1

   Correct Fluid Levels

   If the engine oil is overfilled or contaminated with fuel, drain the oil, replace the oil filter, and refill to the correct specification.

2. 2

   Replace the Breather Filter

   Locate the crankcase breather filter housing on the engine. Remove the cover, extract the old filter element, clean the housing, and install a new OEM breather filter.

3. 3

   Replace the Sensor

   If diagnostic testing proves the crankcase pressure sensor is reading out of range, disconnect the wiring harness, unthread the old sensor from the engine block, and install a new sensor.

4. 4

   Clear Codes and Test

   Use an electronic service tool (EST) to clear the 3458 fault code. Run the engine under load to verify the code does not return.

5. 5

   Internal Engine Repair

   If the code returns and a manual pressure gauge confirms crankcase pressure is genuinely too high, perform a cylinder leak-down test to isolate internal engine wear. Overhaul the cylinder packs or replace the turbocharger as necessary.