B2BEmersonEIMS serves commercial, industrial & institutionalcommercial, industrial, healthcare, telecom, hospitality, government & contractor clients.• Engineering-led • SLA-backed • Documented commissioning
Keyboard Shortcuts
SPN 102 is the boost-pressure signal; the FMI says whether boost is high, low or the sensor is faulty. This page covers HIGH boost (FMI 0, 15, 16): the turbocharger is producing excessive boost pressure beyond normal operating parameters. Over-boost raises peak cylinder pressure and can lead to head gasket failure and engine damage. Common causes are a wastegate or VGT actuator stuck closed or a faulty boost sensor. (Black smoke usually points the other way: too little boost.)
SPN-102 reports intake manifold (boost) pressure. The FMI (Failure Mode Identifier) shown beside it says how the reading is wrong. FMI meanings follow the SAE J1939 standard used by Cummins and most modern diesel engine controllers.
SPN-102 FMI 0
Boost pressure far above normal (most severe) — overboost.
Check first: Wastegate or turbo control, and the sensor reading against a gauge.
SPN-102 FMI 16
Boost pressure above normal (moderately severe).
Check first: Wastegate operation and actuator.
SPN-102 FMI 18
Boost pressure below normal (moderately severe) — low boost.
Check first: Air filter restriction, charge-air or intake leaks, the turbocharger, exhaust leaks before the turbo.
SPN-102 FMI 2
The boost reading is unstable or does not rise with load.
Check first: Oil or soot fouling the sensing port on the intake manifold, and the sensor connector.
SPN-102 FMI 3
The boost sensor on the intake manifold is reporting a voltage too high to be real — usually a broken wire.
Check first: On many engines this sensor also reads intake air temperature; check its connector and the wiring to the manifold.
SPN-102 FMI 4
The boost sensor is reporting a voltage too low to be real — usually a short to ground.
Check first: Wiring near the hot turbo and exhaust side, where insulation hardens and cracks.
SPN 102 covers both high and low boost; the FMI tells you which.
Need parts? Call us with your engine or controller model and we will confirm what we can supply and when.Call +254 768 860 665
High intake manifold pressure (overboost) indicates the turbocharger is producing more boost than designed. This is usually caused by a stuck wastegate or failed boost control system.
Yes, sustained overboost can cause detonation, head gasket failure, piston damage, and connecting rod failure. Stop the engine and repair before continuing operation.
Send us the code or alarm and what the generator is doing, and one of our engineers will help you diagnose it.
Search other controller alarms and engine fault codes, with troubleshooting steps, in Generator Oracle.
Launch Generator Oracle →Full diagnostic guide
A fault code names a symptom, not a cause. Our engineers have written the diagnostic sequence they use on site for this class of fault — ranked causes, ordered steps with the reading expected at each one, and the point at which to stop and call someone.
8 diagnostic steps · intermediate · technician
9 diagnostic steps · intermediate · technician