Code Details
| Display code | SPN 175 FMI 0 |
|---|---|
| SPN | 175 |
| FMI | 0 |
| OEM code | None listed |
| Manufacturer | Cummins |
| System | Engine — lubrication / oil temperature |
| Component | Engine oil cooler / oil temperature sensor |
| Source address | Unknown or not applicable |
| Severity | medium |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-12 |
Plain-English Meaning
The Cummins ISB 6.7 monitors engine oil temperature to protect the lubrication system. Oil that becomes too hot loses viscosity, reducing the protective film on critical engine surfaces. SPN 175 FMI 0 is set when the oil temperature sensor reports a value above the normal range. In most cases this indicates a cooling system problem, an oil cooler restriction, or low oil level. The ISB 6.7 is used in medium-duty trucks, school buses, and vocational equipment where stop-and-go duty cycles can stress the cooling system more than highway operation.
SPN 175 is Engine Oil Temperature in J1939. FMI 0 indicates a value above the normal operating range. On Cummins CM2350 ISB 6.7 engines, the oil temperature sensor is monitored by the ECM. Oil is cooled through an oil cooler integrated into the engine block that transfers heat to the engine coolant. When oil temperature exceeds the calibration threshold, SPN 175 FMI 0 is set. INSITE provides simultaneous monitoring of oil temperature, coolant temperature, and other thermal parameters to help identify the root cause.
Common Symptoms
- Oil temperature or engine warning lamp on the instrument cluster
- High oil temperature reading in Cummins INSITE live data
- Possible concurrent coolant temperature fault if the cooling system is the underlying cause
- Potential oil quality degradation from sustained elevated temperature in vocational or bus applications
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- Cooling system overheat — the oil cooler relies on coolant to absorb heat from the oil
- Oil cooler restriction from scaling or debris reducing heat transfer
- Low engine oil level reducing thermal management capacity
- Oil temperature sensor fault reading above actual temperature
- Severely demanding operating conditions in hot weather or high-load vocational applications
First Checks
- Connect Cummins INSITE and monitor oil temperature alongside coolant temperature — if both are elevated, the cooling system is the root cause
- Check the engine oil dipstick for adequate level
- Inspect the radiator, coolant level, and cooling fan operation if coolant temperature is also elevated
- If coolant temperature is within normal range but oil is high, investigate the oil cooler for restriction or bypass
- Verify the oil temperature sensor reading with a separate temperature measurement if a sensor fault is suspected
Can I Keep Driving?
Sustained high oil temperature increases engine wear. Reduce load or stop if temperatures are significantly above normal. Address the root cause — whether cooling system or oil cooler — before continued high-load or high-ambient-temperature operation.
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
Is the ISB 6.7 oil cooler located inside the engine block?
On the Cummins ISB 6.7, the oil cooler is integrated into the engine block rather than being an external unit. Coolant flows through passages around the oil cooler core, transferring heat from the oil to the coolant circuit. Because the cooler is internal, restriction typically comes from scaling of the coolant passages or the oil passages, rather than external fouling. The cooler is accessed during engine disassembly or through the coolant side with a chemical flush.
Can high ambient temperature alone cause SPN 175 FMI 0 on the ISB 6.7?
Extreme ambient temperatures combined with heavy load operation in stop-and-go duty cycles can stress the ISB 6.7 cooling system, but SPN 175 FMI 0 typically indicates a condition beyond normal operating expectations. If the fault sets only during the hottest parts of the day under heavy load, checking the radiator for clogging, verifying the cooling fan operation, and confirming adequate coolant flow is the appropriate investigation.
Should the engine oil be changed after a high oil temperature event on the ISB 6.7?
A single brief high-temperature event is unlikely to require an immediate oil change if the oil was not significantly overheated for an extended period. However, repeated or sustained high-temperature operation degrades oil quality faster than normal, reducing the oil's ability to protect engine surfaces. If SPN 175 FMI 0 has been active for an extended period or oil sampling shows degradation, an oil change is appropriate before returning the engine to service.