AftertreatmentCaterpillar Diesel ECM

SPN 3391 FMI 5

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 3391-5 is commonly associated with an ARD or aftertreatment regeneration control circuit where current is below normal or the circuit is open. In practical terms, the ECM may be commanding an ARD-related component but not seeing the expected electrical response. This can prevent proper regeneration and cause DPF soot load to increase. The issue should be diagnosed electrically before assuming the DPF or ARD assembly itself is bad.

Likely Causes

Open circuit; damaged wiring; unplugged connector; failed ARD component; blown fuse; poor power or ground; connector corrosion.

What To Check First

Inspect the ARD-related harness and connector, check component resistance if specified, verify power and ground, and run the Cat ET aftertreatment/ARD test.

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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 3474 FMI 31

CAT fault code 3474-31 is typically associated with aftertreatment regeneration or ARD-related operation.

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.

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