BigRigFaults logo
BigRigFaults
☰
Diagnose
Fault CodesProblemsBrandsEnginesCommunityBrandsEnginesGuideAI DiagnosticsTechnical DataCommunity
Log inRegister
Browse Fault Codes
Jump to
Share ↓
FitmentsMeaningImagesDetailed guideOEM/Engine notesCommunity discussionsCommunity videosCommunity notesShare
SPN 94 FMI 4Severity: WarningCummins

SPN 94 FMI 4: Fuel delivery pressure sensor circuit voltage low – hard starts, surging, power loss

Quick Answer

Fuel delivery pressure sensor circuit voltage low – hard starts, surging, power loss

Code
SPN 94 FMI 4
Severity
Warning
Applies to
Cummins
Can I drive?
Driving suitability is not established by this code alone.

Common Symptoms

  • Hard start (especially cold)
  • Surging at idle or under load
  • Low power / hesitation

Likely Causes

  • Fuel pressure sensor wiring short to ground / open circuit
  • Weak lift pump or restriction (filter, gelled fuel in winter)
  • Connector corrosion at sensor

Common Fixes

  • Inspect sensor connector and wiring first (fast and common)
  • Replace clogged fuel filters and confirm winterized fuel
  • Verify lift pump supply pressure meets spec
Full Technical Guide ↓Share This Fault
Full technical sections↓
FitmentsMeaningImagesDetailed guideOEM/Engine notesCommunity discussionsCommunity videosCommunity notesShare

What does SPN 94 FMI 4 mean?

Back to top ↑

Fuel delivery pressure sensor circuit voltage low – hard starts, surging, power loss

Images for SPN 94 FMI 4 (location, common failures)

Back to top ↑
Common rail fuel injection system diagram
Common rail diagram (general). Fuel supply pressure problems can cause rail pressure issues.
Credit: Wikimedia Commons • License: Public Domain
Only use images you own or that have a license allowing commercial reuse (example: CC BY). Attribution alone is not permission.

Detailed guide for SPN 94 FMI 4

Back to top ↑

SPN 94 FMI 4 – Fuel delivery pressure voltage low

Winter adds a bonus layer: **fuel restriction and gelling** can make this code show up alongside real electrical problems.

What drivers usually report

  • Starts rough when cold
  • Feels like it’s starving for fuel on acceleration
  • Acts better after warming up (classic restriction clue)

Fix order that makes sense

1) Electrical checks at the sensor connector

2) Fuel filters and fuel quality

3) Lift pump supply pressure test

BigRigFaults Community

Community discussions related to SPN 94 FMI 4

Compare symptoms, repairs and real-world experience from drivers, technicians and owner-operators.

Browse Community →
Fault Codes / SPN / FMI
SPN 1590 FMI 19 - Meaning, Causes & Diagnostic Discussion
0 replies7 views
Fault Codes / SPN / FMI
SPN 4077 FMI 14 - Meaning, Causes & Diagnostic Discussion
0 replies11 views
Fault Codes / SPN / FMI
SPN 84 FMI 21 - Meaning, Causes & Diagnostic Discussion
0 replies8 views
Fault Codes / SPN / FMI
SPN 1071 FMI 5 - Meaning, Causes & Diagnostic Discussion
0 replies7 views
Still stuck with SPN 94 FMI 4?

Ask the community and include your truck year, make, engine, active codes, symptoms and recent repairs so people can give useful answers instead of performing mechanical astrology.

Ask the Community →

Related fault codes for Cummins

SPN 94 FMI 3: Fuel delivery pressure sensor circuit voltage high – short to power / bad sensor signal
Severity: Warning • Cummins
SPN 157 FMI 7: Fuel rail pressure not responding – rough running, low power, possible no-start
Severity: Critical • Cummins
SPN 5246 FMI 31: DEF Quality - Poor Quality Detected
Severity: Warning • Cummins • Cummins X15
SPN 5394 FMI 31: DEF doser valve condition exists (sticking/crystallization)
Severity: Critical • Cummins • Cummins X15

Mechanic community notes for SPN 94 FMI 4

Back to top ↑

Real-world tips from technicians. Submissions are moderated to keep spam and “my cousin fixed it with duct tape” content out.

No community notes yet. Be the first to add a practical fix that actually works in real life.

Share your fix / advice

Keep it useful: symptoms, what you checked, what fixed it, and whether the code stayed inactive after a drive cycle.

By submitting, you agree it may be edited for clarity and posted publicly after moderation. No spam links.

Share this fault code guide

Help other technicians diagnose SPN 94 FMI 4

WhatsAppFacebookX (Twitter)LinkedInEmailText (SMS)
🔗 https://bigrigfaults.com/faults/spn-94-fmi-4
Back to top ↑