Code Details
| Display code | SPN 100 FMI 1 |
|---|---|
| SPN | 100 |
| FMI | 1 |
| OEM code | None listed |
| Manufacturer | Cummins |
| System | Engine �?lubrication |
| Component | Engine oil pressure / oil pump |
| Source address | Unknown or not applicable |
| Severity | stop safely |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-11 |
Plain-English Meaning
The ISB 6.7 depends on adequate oil pressure to lubricate its bearings, injection pump drive, and other internal components. When pressure falls below the minimum threshold, the ECM activates a warning and may derate the engine. This is a critical fault that requires immediate investigation. On Ford F-650/F-750, International 4300/4400, and Kenworth Class 5-6 trucks with the Cummins ISB 6.7, SPN 100 FMI 1 is a stop-engine fault. Insite provides a fault event snapshot with oil pressure at the time the fault triggered. The ISB 6.7 oil pressure sensor location and oil gallery access point for a mechanical gauge comparison are specific to the engine variant — Insite service data identifies the correct port location. After installing a mechanical gauge, running the engine to operating temperature and comparing mechanical pressure to Insite live data is the definitive sensor accuracy check.
SPN 100 FMI 1 is Engine Oil Pressure below normal. On Cummins ISB 6.7 CM2150/CM2350 engines, the ECM monitors oil pressure from the gallery sensor and triggers engine protection responses based on how far below the threshold the pressure has fallen. Cummins Insite can confirm the actual oil pressure reading and compare it against the minimum expected value at the current RPM and temperature.
Common Symptoms
- Oil pressure warning lamp active
- Possible engine protection derate or wrench light
- Engine noise in severe cases
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- Low oil level from a leak or oil consumption
- Oil pump failure or excessive wear
- Pressure relief valve stuck open
- Wrong oil viscosity
- Internal bearing wear at high mileage
- Faulty oil pressure sensor
First Checks
- Stop the engine and check oil level
- Do not restart without identifying the cause
- After confirming oil level is correct, connect Insite and verify the actual pressure reading
- Compare Insite reading to a mechanical gauge for sensor verification
- Install a mechanical pressure gauge at the ISB 6.7 oil gallery access port and compare to Insite reading
- Check for companion SPN 91 (throttle position) or SPN 110 (coolant) codes that may indicate a multi-sensor event
Can I Keep Driving?
Stop immediately. Operating with confirmed low oil pressure causes irreversible bearing damage rapidly.
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
Why does the Cummins ISB 6.7 in pickups seem more susceptible to oil pressure faults than the ISX15?
The ISB 6.7 in pickup applications is often subjected to more irregular maintenance schedules by private owners compared to fleet-managed ISX15 engines. Extended oil change intervals, wrong oil viscosity (some owners use non-diesel-spec oil), and running with low oil level are more common in private use. Commercial fleets with rigorous maintenance programs rarely experience oil pressure faults on either engine.
Is oil pressure in a Cummins ISB 6.7 in a Ram 3500 the same as in an NPR medium-duty truck?
The ISB 6.7 engine has the same oil pump and lubrication system design across applications. The oil pressure specifications are the same regardless of whether it is in a Ram Heavy Duty pickup, an Isuzu NPR-HD, or a vocational medium-duty chassis cab. The surrounding vehicle chassis and oil capacity may differ, but the engine's minimum pressure requirements are consistent.
Can fuel diluting the engine oil on a Cummins ISB 6.7 reduce oil pressure?
Yes. Fuel dilution reduces oil viscosity. Thinner oil flows past bearing clearances more easily, reducing the ability of the oil film to maintain pressure. In trucks with frequent short trips where DPF regen cycles add fuel to the cylinder bores, fuel dilution can be a real issue. Checking oil viscosity and smelling the oil for fuel contamination is worthwhile if oil pressure is low but the oil level is correct.