SPN 101 - FMI 16 (Fault Code 555)

SPN101 FMI16 (Crankcase Pressure - Data Valid but Above Normal Operational Range)
Fault Code: 555
ISB, ISC, ISL and QSB3.3 CM2150 - Crankcase Pressure Sensor Circuit

PID(P), SID(S): P101
SPN: 101
FMI: 0/16

REASON: Crankcase Pressure - Data Valid but Above Normal Operational Range - Moderately Severe Level.

EFFECT: None on performance.

Circuit Description:
The pressure inside the crankcase filter is measured by the crankcase pressure sensor. When the crankcase pressure sensor determines that the crankcase pressure is higher than normal, this fault code is logged.

Component Location:
The crankcase pressure sensor is located near the crankcase ventilation filter.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine speed is greater than 500 rpm.

Conditions for Setting the Fault Codes:
The ECM detects that the crankcase pressure is greater than a calibrated value.

Action Taken When the Fault Code is Active:

• The ECM illuminates the amber CHECK ENGINE light when the crankcase pressure limit is exceeded.

Conditions for Clearing the Fault Code:
The ECM will turn off the amber CHECK ENGINE light as soon as the crankcase pressure drops below a calibrated value.

Shop Talk:
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM.

Possible causes of this fault code include:
• Crankcase ventilation filter needs to be replaced
• Crankcase pressure sensor damage
• Malfunctioning or misassembled closed crankcase ventilation valve
• Frozen, plugged, or restricted crankcase ventilation hose
• Plugged or restricted crankcase ventilation hose
• Plugged or restricted crankcase ventilation oil drain tube or check valve
• Plugged or restricted crankcase breather tube (Rear Engine Mounted Crankcase Ventilation Filter)
• High air intake restriction.

Depending on the breather system used, the crankcase ventilation filter will be located:
• On top of the rocker lever cover, between the rocker lever cover and the crankcase ventilation filter cover.
• At the rear of the engine, encased in an external crankcase ventilation filter housing that mounts to the flywheel housing.

Both systems are closed crankcase breather systems, meaning the crankcase gases are vented into the intake system at the inlet to the turbocharger compressor. It is important to check for plugged or restricted hoses, tubes, check valves, and filters in extreme cold ambient temperatures. If Fault Code 555 becomes active due to a plugged filter before the maintenance interval is reached or the filter plugs frequently.

Read More:
SPN 157 - FMI 2 (Fault Code 554)
SPN 101 - FMI 0 (Fault Code 556)


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