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ECM Performance — Diesel ECM Programming
EGRMack Diesel ECM

SPN 412 FMI 2

Exhaust gas recirculation valve, cooler, and flow faults.

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System
Mack EGR
Mack ECM Service

Diagnostic Overview

Mack fault code SPN4122 generally indicates erratic or irrational EGR temperature data. The ECM is seeing an EGR temperature signal that does not match expected operating conditions or other temperature sensors. This may create false EGR cooler or flow faults.

Likely Causes

Intermittent EGR temperature sensor; loose connector; chafed harness; sensor drift; exhaust leak; poor ground.

What To Check First

Wiggle-test the harness, inspect connector pins, compare live temperature data, and verify the sensor signal is stable.

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Internal Linking

Related EGR Fault Codes

P0401

Mack fault code P0401 indicates insufficient EGR flow.

P0402

Mack fault code P0402 indicates excessive EGR flow.

P040A

Mack fault code P040A generally relates to the EGR temperature sensor circuit.

P040B

Mack fault code P040B usually indicates an EGR temperature sensor range or performance issue.

P2457

Mack fault code P2457 indicates EGR cooler efficiency below threshold.

SPN 2659 FMI 16

Mack fault code SPN265916 generally points to an EGR flow or EGR mass-flow condition above the expected range.

View All EGR Codes →
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Resolve Mack Code SPN 412 FMI 2 Today

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