SPN 656 FMI 6 — Injector Cylinder 6 Circuit Current Above Normal
High current on injector 6 is isolated before any replacement.
Fault Overview
FMI 6 indicates current above limit on cylinder 6 injector circuit, consistent with shorted coil or short-to-ground.
Engine & Platform Coverage
Symptoms
- •Injector 6 short
- •High current cylinder 6
- •SPN 656 FMI 6
Possible Causes
- 1.Shorted coil
- 2.Harness short to ground
- 3.Incorrect injector
- 4.Oil contamination path
- 5.Damaged insulation
Wiring & Circuit Notes
Abrasion and contamination inspection under cover. Coil and harness shorts dominate. Always verify correct part number on replacement.
DVOM Specs & Sensor Tests
Near-zero resistance indicates short. Disconnect isolation to differentiate injector from harness. Compare to sibling injectors.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
4 steps locked behind Technician Mode- 1Step 1 — Resistance Check: Measure resistance of injector 6. Near-zero indicates internal short. Compare to sibling cylinders.
- 2Step 2 — Disconnect Isolation: Disconnect injector 6 and recheck for short to ground on the harness side.
- 3Step 3 — Harness Visual: Inspect under-cover wiring for abrasion and contact with grounded surfaces.
- 4Step 4 — Spec Verification: Verify correct injector part number and resistance specification.
- 5Step 5 — Confirm Single Circuit: Confirm the fault isolates to cylinder 6 and is not a shared circuit issue.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
Typical Repair Costs
Injector or harness repair $200–800+.
Start Diagnosing This Fault Now
AI Diesel Tech walks you through every evidence gate in the correct order. Choose the plan that fits your shop.
Related Systems
Related Sensor Locations
Common Symptoms
Related Articles
AI Diesel Tech — The Technician's Diagnostic Engine
AI Diesel Tech diagnostic logic is built by an ASE Certified Diesel Technician and engineered for professional shop use. Trusted by technicians nationwide — used in shops, fleets, and training programs.
Summary
Use the AI Diesel Tech diagnostic engine to run this code through a structured, evidence-gated sequence and get a confirmed root cause before any parts are replaced.