Fuel rail pressure too low
The reading is real and it is dangerously low. Low oil pressure, low coolant level and low rail pressure land here. Treat it as a real condition until proven otherwise.
SPN 94 — Fuel rail pressure too low
SPN 94 is the parameter the ECM is flagging on PACCAR, CAT, Mack engines. The FMI that comes with it tells you how it failed. Each failure mode below has its own causes and its own test order — do not treat them as the same repair.
Fuel pressure low
The reading is real and it is dangerously low. Low oil pressure, low coolant level and low rail pressure land here. Treat it as a real condition until proven otherwise.
Fuel delivery pressure low
Real reading, slightly low. Early warning stage.
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