Code Details
| Display code | SPN 101 FMI 0 |
|---|---|
| SPN | 101 |
| FMI | 0 |
| OEM code | None listed |
| Manufacturer | Cummins |
| System | Engine �?crankcase ventilation |
| Component | Crankcase ventilation (CCV) system / piston rings / cylinder liners |
| Source address | Unknown or not applicable |
| Severity | medium |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-11 |
Plain-English Meaning
Crankcase pressure is controlled by the Cummins Crankcase Ventilation (CCV) system, which routes blowby gases from the crankcase back into the intake system for combustion. When pressure builds up above normal levels, it either means too much blowby gas is being produced (worn rings or liners) or the ventilation system cannot vent it quickly enough (plugged filter or blocked hoses). High crankcase pressure can push oil seals and gaskets outward, causing oil leaks.
SPN 101 is Engine Crankcase Pressure in J1939. FMI 0 indicates the measured crankcase pressure is above the normal operating range. On Cummins CM2350 ISX15/X15, the CCV system includes a coalescent filter element that captures oil mist from the blowby gases before they re-enter the intake. As the filter plugs with use, crankcase pressure can rise. Alternatively, high blowby from worn rings directly increases the mass of gas entering the crankcase. Insite provides the live crankcase pressure reading.
Common Symptoms
- Oil leaks from front or rear main seals, valve cover gaskets, or other crankcase seals pushed by internal pressure
- Blue smoke from crankcase ventilation return in the intake area
- Excessive oil consumption
- Check engine lamp active
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- Plugged or overdue CCV filter element restricting blowby gas flow
- CCV system hose or pipe blocked
- Excessive engine blowby from worn piston rings or cylinder liners
- CCV system check valve stuck closed
- Crankcase pressure sensor fault
First Checks
- Check CCV filter service interval �?replace the filter element if overdue or if it has never been replaced
- Inspect the CCV system hoses and connections for blockage or collapsed hoses
- Connect Cummins Insite and monitor crankcase pressure before and after a filter replacement to confirm whether the filter was causing the elevated pressure
- If pressure remains high after filter replacement, perform a blowby test to quantify the rate of blowby and compare against the spec for the engine's mileage and expected wear
Can I Keep Driving?
The engine may still be driveable, but elevated crankcase pressure can push oil past seals and cause leaks. If blowby is the cause, this indicates significant internal wear and further investigation of engine condition is warranted.
Related Codes
Related Lookup Pages
Sources
- Cummins INSITE Service Tool — Public Reference Documentation Cummins Inc. · oem · accessed 2026-06-11 · confidence medium
Source: Cummins Inc., Cummins INSITE Service Tool — Public Reference Documentation. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - QuickServe Online Cummins Inc. · oem · accessed 2026-05-05 · confidence medium
Source: Cummins Inc., QuickServe Online. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - SAE J1939 Standards Collection SAE International · official · accessed 2026-05-05 · confidence medium
Source: SAE International, SAE J1939 Standards Collection. This page paraphrases factual fields only and is not a substitute for the original document.
Open source
FAQ
How often should the Cummins CCV filter be replaced on the ISX15 or X15?
Cummins recommends CCV filter replacement at intervals specified in the maintenance schedule, typically every 150,000 to 250,000 miles depending on the application and duty cycle. Applications with high idle time or lower highway speed ratios may require more frequent replacement. The interval is also listed in the Quickserve maintenance planner.
What is a blowby test and how do I interpret the results on the ISX15?
A blowby test measures the flow rate of gases escaping the piston rings into the crankcase, expressed in cubic feet per minute (CFM) or liters per minute. Cummins specifies acceptable blowby limits for new and in-service ISX15 and X15 engines by displacement and power rating. A blowby rate significantly above the in-service limit indicates ring, liner, or piston wear requiring investigation.
Can high crankcase pressure on the ISX15 cause turbocharger oil seal failure?
Yes. Elevated crankcase pressure increases backpressure on the turbocharger oil drain line, making it harder for oil to flow back to the sump from the turbocharger center section. This can cause oil to be pushed past the turbine-side shaft seal into the exhaust, resulting in blue smoke from the exhaust and turbocharger oil consumption. Resolving the crankcase pressure fault is important for turbocharger longevity.