Mack EGR Fault Codes

Mack fault code P0401 indicates insufficient EGR flow.

Mack fault code P0402 indicates excessive EGR flow.

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

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

Mack fault code P2457 indicates EGR cooler efficiency below threshold.

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

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

Mack fault code SPN4120 generally indicates an EGR temperature value above the expected range.

Mack fault code SPN4122 generally indicates erratic or irrational EGR temperature data.

Mack fault code SPN4125 generally indicates an EGR temperature sensor circuit current below normal or open-circuit type condition.

Mack fault code SPN47527 generally relates to an EGR control, EGR cooler bypass, or EGR flow-control mechanical response problem depending on calibration.