LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 1998 >> 4Runner Base, 4WD, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes - 4-Cylinder >> Self-Diagnostic Tests >> DTC P0402: Excessive Exhaust Gas RECIRCULATION (EGR) Flow Detected >> Diagnosis & Repair (Using OBD-II Scan Tool)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Disconnect EGR temperature sensor. Sensor is located near EGR valve. Using ohmmeter, measure resistance between sensor terminals. If resistance is 2500 ohms or more, go to next step. If resistance is less than 2500 ohms, replace sensor.
  2. Check for short circuit in wiring harness between EGR temperature sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  3. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 33-39 ohms at 68°F (20°C). Check for continuity between each terminal and body of VSV. If continuity exists, replace VSV. If continuity does not exist, go to next step.
  4. Check VSV operation. Apply battery voltage to VSV terminals. Apply air pressure to VSV port "E". See Figure. Air from port "E" should flow from port "F". Remove battery voltage from VSV terminals. Air from port "E" should not flow from port "F". Replace VSV as necessary. If VSV operates as specified, check EGR valve. See appropriate SYSTEM/COMPONENT TESTS article. If EGR valve is okay, go to next step.
  5. Check for open circuit in wiring harness between engine compartment fuse block and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, replace ECM.
scientia non olet · About LEMON Manuals