EGRMack Diesel ECM

P040A

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

Exhaust gas recirculation valve, cooler, and flow faults.

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System

Mack EGR

Mack ECM Service

Diagnostic Overview

Mack fault code P040A generally relates to the EGR temperature sensor circuit. The ECM uses EGR temperature feedback to monitor EGR cooler operation and EGR flow. An incorrect reading can affect emissions control and may create false EGR cooler or flow faults.

Likely Causes

Failed EGR temperature sensor; open or shorted circuit; connector corrosion; damaged harness; exhaust leak; sensor contamination.

What To Check First

Compare EGR temperature live data cold and warm, inspect wiring and connector condition, and verify the sensor circuit.

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Internal Linking

Related EGR Fault Codes

View All EGR Codes

P0401

Mack fault code P0401 indicates insufficient EGR flow.

P0402

Mack fault code P0402 indicates excessive EGR flow.

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.

SPN 2659 FMI 18

Mack fault code SPN265918 generally points to EGR flow or EGR mass flow below the expected range.

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