Detailed guide for SPN 102 FMI 18
Back to top ↑What SPN 102 FMI 18 means
SPN 102 identifies intake manifold pressure. FMI 18 indicates that the pressure is below the normal operating range at a moderately severe level.
Detroit documentation describes SPN 102 FMI 18 as intake manifold pressure lower than expected under load.
What you may notice
The malfunction indicator lamp or check-engine light may illuminate.
Engine reaction depends on the emissions generation and calibration. Some documented Detroit applications have no commanded engine reaction, while others can apply a 25 percent derate.
What to check first
Check for other active faults involving the turbocharger actuator, intake manifold pressure sensor or barometric pressure sensor. Diagnose those faults first when required by the OEM procedure.
Inspect the front air path, air filter, intake piping, charge-air cooler, boots, clamps and related plumbing for restrictions or leaks.
Check the charge-air system carefully because even a leak that is difficult to see while parked can cause boost pressure to fall below the expected value under load.
Compare intake manifold pressure with barometric pressure under the conditions specified by the manufacturer.
If the readings are implausible, inspect the manifold pressure sensor, connector and wiring.
Important
Do not assume SPN 102 FMI 18 automatically means the turbocharger has failed. Air-system leaks, restrictions, sensor problems and turbo-control issues can all contribute to low intake manifold pressure.
The exact diagnostic thresholds and verification drive cycle vary by engine generation and calibration.
Mechanic community notes for SPN 102 FMI 18
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