P1661moderate severityPowertrain

EGR Circuit Malfunction

on 2000 Toyota 4Runner 3.4L V6 · RWD

What this code means

The ECM detected a fault in the EGR system control circuit.

Symptoms

  • CEL
  • Rough idle
  • Hesitation
  • Increased NOx
  • Failed emissions

Common causes

  • Faulty EGR solenoid
  • Carbon clogged passages
  • Damaged wiring
  • Vacuum leaks

Diagnostic steps

  1. Test EGR solenoid
  2. Clean EGR passages
  3. Inspect wiring
  4. Check vacuum supply

Repair notes

Clean or replace EGR components.

Other Powertrain codes on this vehicle

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