Cummins ISX12 CM2250 (2010-12) Fault Code: 3348 PID: SPN: 1176 FMI: 1 Turbocharger 1 Compressor Inlet Pressure- Data Valid But Below Normal Operating Range- Most Severe Level

Circuit Description
The ECM calculates a differential pressure across the turbocharger using the intake manifold pressure sensor and the crankcase pressure sensor.

Component Location
The intake manifold pressure sensor is located in the air intake horn. The crankcase pressure sensor is mounted to the crankcase breather filter housing.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes
The calculated differential pressure across the turbocharger is greater than a threshold.

Action Taken When the Fault Code is Active
The ECM illuminates the red STOP ENGINE lamp immediately when the diagnostic runs and fails.
An engine speed derate will occur when the fault is registered.
If the problem persists for 5 minutes, an engine shutdown procedure will begin.
Conditions for Clearing the Fault Code
To validate the repair, start the engine and let it idle for 1 minute.
The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
The ECM will turn off the red STOP ENGINE lamp after the diagnostic runs and passes.
The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults.

Shop Talk
Possible causes of this fault code include:

Crankcase filter needs to be changed.

If the crankcase filter is being replaced frequently for this fault code, reference the Crankcase Coalescing Filter – Frequent Replacement troubleshooting symptom tree.
Air intake filter needs to be changed.

Use the following procedure for air intake filter replacement in the approprate service manual. Refer to Procedure 010-031 in Section 10.
A plugged or restricted crankcase ventilation system.

Check the tube between the engine and the coalescing filter.
Check the draft tube going from the coalescing filter to the atmosphere or intake manifold.
Consider the working environment. Ice, snow, or mud can temporarily block the tube and then fall away.
Complete the entire troubleshooting tree whether Fault Code 3348 is active or inactive.

If a problem is found in the early steps, the troubleshooting tree should still be completed.

Possible Cause:
1) Intake Manifold temperature/pressure sensor failure
2) ECM calibration