Case IH F-101-01 - ECU – Engine Control Unit (ECU): Crankcase pressure sensor voltage is lower than expected

The voltage signal returning from the crankcase pressure sensor to the control module is below the minimum expected threshold, indicating the circuit is shorted to a low source, the line is disconnected, or there is an internal failure in the sensor or ECU.

• MAGNUM AFS Connect
• 5140
• 6140
• 6150
• 7140
• 7150
• 7240
• 7250
• 8240
• 8250
• 9240
• 9250
• 1021G
• 1121F
• 1121G

1. 1

   Check battery voltage to ensure it is not lower than expected, as low voltage can disable ECU powerstage diagnosis and cause false readings

2. 2

   Inspect the sensor wiring harness and connectors for a short circuit to a low source or a disconnected line

3. 3

   Check for correlated ECU faults, specifically an ambient pressure sensor fault, which indicates an internal ECU failure

4. 4

   Verify engine oil level to ensure it is not overfilled, as oil system anomalies can cause erratic crankcase pressure readings

1. 1

   Repair wiring

   Resolve any wiring shorts to ground or repair disconnected lines in the sensor harness.

2. 2

   Diagnose sensor failure

   If the wiring is intact and the ECU is supplying the correct reference voltage, the sensor itself has failed internally and must be replaced.

3. 3

   Replace sensor

   Remove the old crankcase pressure sensor from the engine block and install the replacement unit.

4. 4

   Clear codes and verify

   Clear the ECU fault codes and verify that the sensor value is now reading as 'plausible'.