SPN 157 FMI 1 — Injector Metering Rail 1 Pressure - Data Valid But Below Normal Operating Range (XPI common rail fuel pressure too low)
What it means: Injector Metering Rail 1 Pressure - Data Valid But Below Normal Operating Range (XPI common rail fuel pressure too low).
How serious / can you keep driving: Critical. Stop as soon as it's safe.
Check first: 1) Gauge fuel supply pressure at the filter housing inlet - check against spec, typically 85-120 psi range depending on filter condition
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Listed providers nearest Indianapolis, IN
Closest first. Tell them SPN 157 FMI 1 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Indianapolis, IN · (317) 789-5002
- 0.0 mi away — based in Indianapolis, IN · (317) 300-7000
- 0.0 mi away — based in Indianapolis, IN · (317) 646-8208
Applies to: Cummins Isx15 · Freightliner Cascadia · International ProStar (ISX15 2013-2019) · Kenworth T680 · Peterbilt 579
What SPN 157 FMI 1 means
Injector Metering Rail 1 Pressure - Data Valid But Below Normal Operating Range (XPI common rail fuel pressure too low).
How serious is it?
Critical. Stop as soon as it's safe.
Most likely causes
- Restricted primary or secondary fuel filter starving the high-pressure pump of supply fuel
- Air ingestion on the suction side between tank and gear pump
- a weak/failing low-pressure lift (gear) pump
- a stuck or failing rail pressure control valve (PCV) on the high-pressure pump
- a collapsed or pinched fuel supply line
First moves (roadside)
- 1) Gauge fuel supply pressure at the filter housing inlet - check against spec, typically 85-120 psi range depending on filter condition
- low reading points to a restricted filter or weak lift pump. 2) Inspect suction-side fittings from the tank to the gear pump for an air leak. 3) With INSITE, compare desired versus actual rail pressure - a large persistent gap with good supply pressure points to the fuel pump pressure control valve (PCV), not the rail itself
FAQ
Injector Metering Rail 1 Pressure - Data Valid But Below Normal Operating Range (XPI common rail fuel pressure too low).
Critical — Stop as soon as it's safe.
The most common cause is: Restricted primary or secondary fuel filter starving the high-pressure pump of supply fuel. Other possibilities include Air ingestion on the suction side between tank and gear pump; a weak/failing low-pressure lift (gear) pump; a stuck or failing rail pressure control valve (PCV) on the high-pressure pump; a collapsed or pinched fuel supply line.
Stop as soon as it's safe. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside SPN 157 FMI 1, or share the same subsystem.
- Injection Rail Pressure — Below Normal (SPN 157 FMI 18)
- Injector Metering Rail 1 Pressure - Data Valid But Above Normal Operating Range (XPI common rail fuel pressure too high) (SPN 157 FMI 0)
- Fuel Delivery Pressure — Low (SPN 94 FMI 1)
- Injector #1 open circuit (SPN 651 FMI 5)
- Injector #2 open circuit (SPN 652 FMI 5)
- Injector #3 open circuit (SPN 653 FMI 5)
- Injector #4 open circuit (SPN 654 FMI 5)
- Injector #5 open circuit (SPN 655 FMI 5)
Same symptom: Fuel delivery
Other codes on the tank-to-injector path — pressure, filters, water and the pump.
- Fuel System Leak Detected - Large Leak (P0093) · Fuel System
- HP Fuel Rail Pressure Low During Power Enrichment (P1093) · Fuel System
- High-Pressure Fuel System Relief Valve Open (P2BAD) · Fuel System
- Injector #6 open circuit (SPN 656 FMI 5) · Fuel System
- Fuel Rail/System Pressure Too Low (P0087) · Fuel System
- Fuel Rail/System Pressure Too High (P0088) · Fuel System
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.