What Is Fault Code SPN 101 FMI 16? (Crankcase Pressure)

There may be those people who do not know what the term ‘crankcase’ means. This is the metal casing of the engine block that not only holds the crankshaft but also the majority of oil in your engine. When the crankcase pressure changes, you do have a problem.

The code SPN 101 means Engine Crankcase Pressure Crankcase Pressure - Data Valid But Above Normal Operating Range - Moderately Severe Level. Its Cummins equivalent code is 555. The amber light should be illuminated when this code is set.

To learn more about this code and what to do about it, just continue to read our article. It has the information you want to know about so you can handle the problem promptly. However, there should be no effect on engine performance.

SPN 101 FMI 16


As you can see, this is an issue of pressure. The significance of this code is that you may have an internal engine problem that created a blow-by situation. The crankcase pressure sensor is responsible for setting this code and its location is near the crankcase breather filter.

The sources for this code are: plugged or restricted hoses, tubes, check valves, oil separators, and filters especially if you are in the colder months of the year. If the code sets before the regularly scheduled maintenance time, then the possible sources can be-

- Crankcase breather filter needs to be replaced

- Crankcase pressure sensor damage

- Plugged or restricted crankcase breather oil separator

- Plugged or restricted crankcase breather oil drain tube or check valve

- Plugged or restricted crankcase breather draft tube

- Frozen plugged, or restricted crankcase breathe

You will have to check your ECM to make sure it is calibrated correctly. This can be done through QuickServe Online. If it is not calibrated or corrected do that fix first.

If you are having trouble finding the crankcase ventilation filter then it can be located on top of the rocker level cover, between the rocker level cover & the crankcase ventilation filter cover.

Or on other engines, it can be found at the rear of the engine inside an external crankcase ventilation filter housing that is attached to the flywheel. (source)

SPN 101 FMI 2


This code is explained as- Sensor Drift Fault For Crankcase Pressure: Fmm_as_et_test2 Condition Exists; Sensor Drift Fault For Crankcase Pressure on the official SPN fault code list.

Is Cummins fault code equivalent is 1942 and that fault code list says- Engine Crankcase Pressure Crankcase Pressure - Data erratic, intermittent, or incorrect, and an amber light should appear as well. Here are the steps you need to take to resolve this issue:

1 Check for primary fault codes

2 External oil leak

3 Visual inspection of crankcase breather components

4 Crankcase pressure sensor stuck in-range

5 Crankcase breather restriction check

5.1 Crankcase pressure sensor or breather element check

6 ECM calibration revision history check

7 Crankcase pressure sensor is malfunctioning (source)

In this case, each of those 7 steps has its own page of instructions and information. There are too many to place here but the first step is to turn the ignition to ON and then attach the Cummins diagnostic tool.

After that, you need to clear any other fault codes that appear with this one on your diagnostic tool or dash. Some of the following steps are just having you do visual inspections first to see if there are any visibly damaged parts.

The best thing to do is go through those instructions and make sure to follow them carefully. You may not have to do all 7 steps to clear this code.

Cummins Code SPN 101 FMI 0


This code’s Cummins equivalent is 556 and it says- Engine Crankcase Pressure Crankcase Pressure - Data valid but above normal operational range - Most Severe Level.

If you look up this code on the official SPN fault code list, you may not see the words ‘most severe level’. The explanation there is long and it says- Crankcase Pressure Sensor Rationality High Monitor: Fmm_as_et_test2 Condition Exists; The Fault Will Enable When The "live Crankcase Pressure Curve" Is Above The "baseline Crankcase Pressure Curve" By A Calibratable Threshold.

You should see a red light illuminated on your dash. The steps you need to take are as follows:

1 Check for primary fault codes

2 Lubricating oil level is incorrect

3 Plugged external crankcase breather tube

4 Crankcase pressure sensor stuck in-range

5 Crankcase Blowby Check

5.1 Turbocharger leaking air into the crankcase

5.2 Air compressor leaking air into the crankcase

5.3 Worn or damaged power cylinder components

6 ECM calibration revision history check (source)

Some of the sources for this code are the same as listed for SPN 101 FMI 16 above. The first step is the same as the first step in SPN 101 FMI 2. The instructions for the first step are:

Before troubleshooting, this fault code, troubleshoot any fault code that is active or has more than one inactive count within the last 25 engine operating hours from the following list:

- Crankcase pressure: 1843, 1844, 3733, 3734”

There are only six pages of instructions to read and follow so this repair will only take as long as it takes to search for the problem and replace the failed or damaged part.

Make sure to read each step carefully as you may be turning the engine off and on several times throughout the repair process.

Some Final Words

The crankcase is a vital engine part. Without it, you would have no lubrication for other vital engine components and you would have no place to store your oil.

While some of these codes are not going to derate your vehicle, and you can still drive it. But, do not drive too far or too fast to the repair shop. It is not a code you should ignore for very long, especially when the red light is lit up.

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