Fuel Shutoff Valve - Current Above Normal
The CUMMINS-255 (Cummins) diesel fault code means: Fuel Shutoff Valve - Current Above Normal. This is a critical severity code.
- Keep driving?
- No — stop driving
- DIY difficulty
- advanced
- Estimated cost
- $350-$1,100
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View pilot availability →What Are the Symptoms of CUMMINS-255?
- Engine protect mode or forced shutdown
- Hard starting or extended cranking
- Power loss under load
- Rough idle and stalling
- Black smoke or white smoke at exhaust
- Poor fuel economy
What Causes CUMMINS-255? (Most Likely First)
- Failed high-pressure fuel pump (CP3 or CP4) Likely
- Clogged fuel filters (primary or secondary) Very Likely
- Failed or stuck fuel rail pressure regulator Likely
- Leaking or stuck injector Possible
- Weak lift pump causing low supply pressure Possible
- Wiring or harness damage at injector or rail Less Likely
Can I Still Drive with CUMMINS-255?
No — stop driving. CUMMINS-255 is rated critical severity. Continuing to drive in this state risks further damage — get it looked at before your next trip.
Frequently Asked Questions
What is Cummins fault code 255?
Cummins fault code 255 indicates: Fuel Shutoff Valve - Current Above Normal. It is a critical-severity fault in the fuel delivery system.
Can I drive with Cummins fault code 255?
No. Fault code 255 triggers protective engine shutdown or severe derate. Continued operation risks engine damage or stranding. Tow to a Cummins dealer or qualified diesel shop.
How much does it cost to fix Cummins fault 255?
Repair cost is approximately $350-$1,100 including parts, labor, and any dealer programming required. DIY repairs (sensor replacement) fall at the low end; pump, aftertreatment, or ECM work falls at the high end and usually requires INSITE diagnostic software.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose CUMMINS-255?
Connect INSITE, command injector cutout test, and observe RPM drop per cylinder to localize injector faults.
Verify fuel rail pressure on INSITE matches commanded pressure (within 10%) at idle and under load.
Inspect both fuel filters (primary/water separator and secondary) for restriction -- replace if overdue.
Check lift pump supply pressure at inlet to CP3/CP4 high-pressure pump (spec varies, typically 5-10 psi).
Inspect fuel return line flow per injector using a return-line test kit to spot a leaking injector.
Check fuel for water contamination and microbial growth -- drain water separator before starting.
If high-pressure pump is suspect, perform a pump low pressure test; replace pump and contaminated fuel if failed.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J1939-73Application Layer: Diagnostics (defines the SPN/FMI fault-identifier framework)
Which Vehicles Commonly Get CUMMINS-255?
- Peterbilt 579, 567 with Cummins ISX/X15
- Kenworth T680, T880 with Cummins X15
- Ram 2500/3500 with 6.7L Cummins
- Ram 4500/5500 with 6.7L Cummins
- Freightliner M2 106 with Cummins ISL9/L9
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