What are the symptoms of SPN 3359 FMI 0?

Check engine light illuminated. NOx sensor fault active. Poor NOx conversion efficiency. Aftertreatment system performance degraded. DEF consumption may be higher than normal. Possible derate or reduced power

What causes SPN 3359 FMI 0?

NOx sensor 1 heater circuit over-temperature due to extended high exhaust temperature operation Faulty NOx sensor 1 with internal heater element failure causing over-current Exhaust system temperature spike from uncontrolled regeneration event Short to voltage in NOx sensor heater control circuit causing excessive heater duty cycle ACM/ECM software miscalculation of heater control duty cycle Damaged or corroded NOx sensor connector causing increased resistance and heat buildup NOx sensor installed in incorrect location causing abnormal thermal exposure

How do I diagnose SPN 3359 FMI 0?

Full step-by-step DVOM tests, electrical procedures, and connector pinout data for SPN 3359 FMI 0 are available inside the AI Diesel Tech guided diagnostic session. The AI walks you through every test — one step at a time.

SPN 3359 FMI 0AftertreatmentInducement Risk

NOx Sensor 1 Heater - Data Valid But Above Normal

Run Full Diagnosis View Related Faults See OEM System Guide

Scan Tool — in guided session

DVOM Testing — in guided session

Connector Pinout — in guided session

DieselVision™ Upload photos — DieselVision™ reads diagrams, connectors, and screens with precision.

Overview

Fault Code

SPN 3359 / FMI 0

Common Symptoms

Check engine light illuminated
NOx sensor fault active
Poor NOx conversion efficiency
Aftertreatment system performance degraded
DEF consumption may be higher than normal
Possible derate or reduced power

Root Causes

NOx sensor 1 heater circuit over-temperature due to extended high exhaust temperature operation Faulty NOx sensor 1 with internal heater element failure causing over-current Exhaust system temperature spike from uncontrolled regeneration event Short to voltage in NOx sensor heater control circuit causing excessive heater duty cycle ACM/ECM software miscalculation of heater control duty cycle Damaged or corroded NOx sensor connector causing increased resistance and heat buildup NOx sensor installed in incorrect location causing abnormal thermal exposure

Full step-by-step tests, DVOM guidance, and pinout data are available inside the AI Diesel Tech diagnostic session.

AI walks you through every test — one step at a time. Plans start at $12.95/mo.

Start Guided Diagnosis See How It Works

Derate Behavior

Power Derate

Yes

SCR Inducement Risk

If left unresolved, this fault may trigger SCR inducement — a progressive derate enforced by the ECM to ensure emissions compliance.

System Interactions

SPN 3359 FMI 0 interacts with the following systems and may trigger cascading faults if not resolved promptly.

DPF differential pressure monitoring — soot load calculations affected

SCR NOx conversion efficiency — DEF dosing strategy may be altered

Active regen inhibit logic — regen may be blocked or delayed

Engine protection derate — ECM may reduce power to protect components

Common Diagnostic Mistakes

Replacing the sensor without verifying wiring continuity and supply voltage first.

Clearing codes without identifying and resolving the root cause — the fault will return.

Ignoring related active faults — cascading faults often share a root cause.

Skipping the connector inspection — corrosion and damaged pins are a leading cause of sensor faults.

Condemning the ECM before exhausting all wiring and component tests.

Replacing the DPF without verifying the regen system is functional — a failed regen injector will reload the new DPF.

Ignoring DEF quality — contaminated DEF causes SCR efficiency faults that look like hardware failures.

Related Faults in This Category

SPN 5246-31SCR NOx Efficiency Low SPN 4364-18DEF Dosing Below Normal SPN 3364-2DEF Quality Erratic SPN 3251-0DPF Differential Pressure High SPN 3719-16DPF Soot Load High

OEM System Resources

Cummins Fault Codes Detroit Diesel Fault Codes PACCAR Fault Codes Volvo Fault Codes Freightliner Fault Codes Mack Fault Codes

ASE Training Resources

Why ASE Certification Matters How ASE Tests Work ASE Study Tips ASE vs AI Diesel Tech Certification Paths Get Started with ASE

Diagnostic Engine v7.0

Diagnose SPN 3359 FMI 0 Now Start New Diagnosis

Authority References

Diagnostic procedures on this page are informed by OEM service literature and industry standards.

EPA Aftertreatment & Emissions GuidelinesU.S. EPA heavy-duty diesel aftertreatment compliance, DPF/SCR regulations, and NOx standards.Cummins QuickServe OnlineOfficial Cummins service manuals, fault code lookup, and TSB database.Detroit Diesel DiagnoCentralDetroit Diesel diagnostic procedures, DDDL documentation, and service literature.PACCAR MX Engine ServicePACCAR MX-11 and MX-13 engine service documentation and DAVIE diagnostic guides.Volvo/Mack Tech ToolVolvo and Mack engine fault code reference and PTT/Tech Tool diagnostic procedures.ASE — Diesel Truck Technician CertificationNational Institute for Automotive Service Excellence — T2 Diesel Engines certification standards.

Get weekly diesel diagnostic tips

Real-world fault code walkthroughs, wiring tips, and shop-tested fixes — free.

No spam. Unsubscribe anytime.

Get AI-Guided Diagnosis for SPN 3359 FMI 0

The diagnostic engine walks you through every physical test — step by step, on your phone, at the truck. No guessing. No wasted parts.