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ECM Performance — Diesel ECM Programming
AftertreatmentCaterpillar Diesel ECM

FMI

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

System
Caterpillar Aftertreatment

Needs VerificationThis code as listed may be incomplete or non-standard (e.g. a partial code, placeholder term, or reference number rather than a confirmed fault code). Pull the exact code in the Cat ET tool before using this page for a repair decision.

Diagnostic Overview

FMI is not a fault code by itself. It means Failure Mode Identifier and describes how the ECM sees the problem, such as voltage high, voltage low, data erratic, current below normal, or condition above normal. For CAT diagnostic work, the SPN identifies the system or signal and the FMI explains the failure type. A code list that only says FMI is incomplete and must be matched with an SPN or Cat event code before a technician can diagnose it accurately.

Likely Causes

Incomplete code information; missing SPN number; scanner display truncation; copied code list without the failure mode detail.

What To Check First

Retrieve the complete SPN and FMI combination from Cat ET or the machine display before diagnosing or ordering parts.

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Related Aftertreatment Fault Codes

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