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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 5 (Engine Controls - Tests W/Codes - 2.3L) >> Circuit Tests >> DTC P0400 - EGR Flow Malfunction >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

WARNING: This page is about a different car, the 1997 Mazda Millenia. However, it is still accessible from the selected car via links, so may be relevant.
  1. Determine if any other EGR or MAP related DTCs are present. Diagnose and repair those DTCs first. If no other EGR related DTCs are present, go to next step.
  2. Inspect the EGR valve position sensor. See appropriate SYSTEM/COMPONENT TESTS - 2.3L article. Replace as needed. If EGR valve position sensor is okay, go to next step.
  3. Inspect all EGR vent and vacuum hoses. Repair or replace as needed. If all hoses are okay, go to next step.
  4. Inspect the Manifold Absolute Pressure (MAP) sensor. See appropriate SYSTEM/COMPONENT TESTS - 2.3L article. Replace as needed. If MAP sensor is okay, go to next step.
  5. Inspect all MAP sensor and solenoid hoses. Repair or replace as needed. If all hoses are okay, go to next step.
  6. Erase DTCs. See CLEARING CODES  in SELF-DIAGNOSTIC SYSTEM section. If DTC resets, replace ECM. If DTC is not present, intermittent poor harness connection may have caused DTC to originally set.
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