Code Details
| Display code | SPN 102 FMI 1 |
|---|---|
| SPN | 102 |
| FMI | 1 |
| OEM code | None listed |
| Manufacturer | Cummins |
| System | Engine �?turbocharger / charge air |
| Component | Turbocharger / charge air cooler / boost pressure sensor |
| Source address | Unknown or not applicable |
| Severity | medium |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-11 |
Plain-English Meaning
The ISB 6.7 uses a variable geometry or wastegate turbocharger to build boost for efficient combustion. When actual boost falls below the commanded target, the engine reduces fueling to prevent overfueling, resulting in noticeable power loss. This is a common fault on higher-mileage ISB 6.7 engines as the turbocharger wears. On Ford F-650/F-750, International, and Kenworth Class 5-6 trucks with the Cummins ISB 6.7, the boost pressure sensor monitors the charge air circuit downstream of the turbocharger compressor. Insite provides a boost pressure comparison against commanded target at various load points, which helps identify whether the shortfall is from sensor error, boost leak, or turbocharger efficiency loss. The ISB 6.7 VGT actuator position is visible in Insite live data and a sluggish or fixed VGT position is a confirmed cause of below-normal boost.
SPN 102 FMI 1 is Engine Intake Manifold Pressure below normal. On Cummins ISB 6.7 CM2150/CM2350, Insite provides commanded and actual boost simultaneously. The ISB 6.7 uses either a VGT or a wastegate turbocharger depending on the model year and application �?the diagnosis approach differs slightly between the two designs.
Common Symptoms
- Power loss under load
- Sluggish throttle response
- Possible black smoke from under-boosted combustion
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- VGT actuator fault or wastegate stuck open
- Charge air cooler or intercooler pipe boost leak
- Severely restricted air filter
- Turbocharger compressor wheel damage or bearing wear
- Boost pressure sensor fault
First Checks
- Connect Cummins Insite and compare commanded vs. actual boost at idle and under load
- Inspect charge air hoses and clamps for leaks
- Check air filter restriction indicator
- Use Insite to check for VGT actuator fault codes if VGT-equipped
- Compare actual boost pressure to commanded boost in Insite under load
- Check VGT actuator position response in Insite live data during a throttle transient
Can I Keep Driving?
Driveable with reduced power. Avoid sustained heavy loading until the boost deficiency is diagnosed and repaired.
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
Does the Cummins ISB 6.7 use a VGT or a wastegate turbocharger?
Early ISB 6.7 applications used a wastegate turbocharger. Later CM2150 and CM2350 variants may use a VGT design for improved EGR control. The specific turbocharger type varies by model year, power rating, and application. Cummins Insite or Quickserve can confirm the turbocharger type for the specific engine serial number.
Can a failed EGR valve cause low boost on the Cummins ISB 6.7?
A stuck-open EGR valve allows exhaust gas to recirculate in excess, diluting the fresh air charge. This reduces the effective oxygen content entering the cylinder but does not directly reduce turbocharger boost pressure as measured in the intake manifold. However, if the EGR fault is causing the VGT to be commanded to a position that reduces boost, an indirect connection is possible.
How does a boost leak affect the ISB 6.7 in a Ram pickup vs. a medium-duty truck?
A boost leak affects the ISB 6.7 the same way regardless of the application �?it reduces the pressure at the intake manifold sensor below the commanded target. In a pickup, the driver may notice reduced towing capability and throttle response. In a medium-duty truck, the power reduction under load may be more noticeable due to the heavier base vehicle weight and typical load profiles.