AftertreatmentCaterpillar Diesel ECM

SPN 3474 FMI 31

Name: ECM Performance
Address: Fort Lauderdale, FL, 33325, US
Telephone: (888) 768-2447
Price range: $$-$$$

DPF, DEF, SCR, and NOx-reduction system faults.

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System

Caterpillar Aftertreatment

Caterpillar ECM Service

Diagnostic Overview

CAT fault code 3474-31 is typically associated with aftertreatment regeneration or ARD-related operation. The ECM may be unable to complete the requested regeneration event or may be detecting that the aftertreatment fuel/combustion process is not behaving as expected. This code can appear with DPF soot loading, failed regeneration attempts, or ARD fuel and air delivery problems. It should be diagnosed with active codes, regen history, exhaust temperature readings, and soot-load data rather than cleared repeatedly.

Likely Causes

Failed or incomplete regeneration; ARD fuel delivery issue; restricted ARD air supply; plugged DPF; faulty exhaust temperature sensor; exhaust leak; excessive soot from engine problem.

What To Check First

Review regen history and soot level, inspect ARD fuel and air components, verify exhaust temperature sensors, and check for DPF restriction or upstream soot-producing faults.

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Related Aftertreatment Fault Codes

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SPN 1761 FMI 17

CAT fault code 1761-17 commonly relates to diesel exhaust fluid level or a DEF level signal that is below the expected range.

SPN 3360 / SPN 3820

CAT codes listed as 3360/3820 generally point toward the DEF supply, DEF quality, DEF tank, or SCR dosing system depending on the exact FMI shown in Cat ET.

SPN 3361 / SPN 3821

CAT codes listed as 3361/3821 commonly belong to the DEF dosing or SCR control side of the aftertreatment system.

SPN 3701 FMI 15

CAT fault code 3701-15 commonly indicates an aftertreatment condition that is above normal but at a least-severe level, often connected with DPF soot load, regeneration need, or aftertreatment restriction.

SPN 3701 FMI 16

CAT fault code 3701-16 usually represents a more serious aftertreatment condition than 3701-15, with the measured or calculated value above normal at a moderate severity level.

SPN 3719 FMI 0

CAT fault code 3719-0 is generally an aftertreatment soot-load or DPF restriction code at a high-severity level.

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