Diagnostic Overview
Mack fault code P046C64 generally points to an EGR differential pressure sensor range or performance problem. Even though the sensor is part of the EGR/air-handling system, incorrect EGR pressure feedback can affect emissions control, soot production, regeneration behavior, and overall aftertreatment performance. The ECM is seeing a signal that does not match expected EGR flow or pressure conditions.
Likely Causes
Faulty EGR differential pressure sensor; plugged or leaking pressure tubes; carbon buildup in EGR passages; exhaust or intake leaks; damaged wiring; poor connector contact.
What To Check First
Inspect the EGR differential pressure sensor, tubes, ports, and connector. Compare live pressure data with key-on/engine-off and running conditions before replacing parts.