SPN 157 / FMI 1
Injection Rail Pressure — Below Normal (Most Severe)
SAE J1939
fuel
SPN 157
FMI 1
What it means
Rail pressure too low — HPFP wear, leak, or regulator.
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SPN 157 / FMI 0
Injection Rail Pressure — Above Normal (Most Severe)
fuelHigh
SPN 94 / FMI 1
Fuel Delivery Pressure — Below Normal (Most Severe)
fuelHigh
P0087
Fuel Rail/System Pressure Too Low
fuelHigh
P0088
Fuel Rail/System Pressure Too High
fuelHigh
P062D
Fuel Injector Driver Circuit (Bank 1)
fuelHigh
P1093
Fuel Rail Pressure Low
fuelHigh
General reference only — always confirm against the OEM procedure for your specific engine.