P0403moderate severityPowertrain

EGR Control Circuit

on 1998 Mazda 626 2.0L I4 · FWD

What this code means

Malfunction in the EGR valve control circuit (electrical EGR valves).

Symptoms

  • Check Engine Light
  • EGR not functioning
  • Increased emissions

Common causes

  • Faulty EGR valve
  • Wiring damage
  • PCM driver failure
  • Corroded connector

Diagnostic steps

  1. Test EGR valve solenoid resistance
  2. Check wiring
  3. Command EGR with scan tool
  4. Test PCM output

Repair notes

Replace EGR valve or repair wiring.

Other Powertrain codes on this vehicle

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