LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 1997 >> Tacoma SR5, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes - 2.4L >> Circuit 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. EGR temperature sensor is located on intake air chamber. Using ohmmeter, measure resistance between EGR temperature sensor terminals. If resistance is 2500 ohms or more, go to next step. If resistance is less than 2500 ohms, replace EGR temperature sensor.
  2. Check for short circuit in wiring harness between EGR temperature sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS - 2.4L article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  3. Access ECM behind glove box. Disconnect ECM E8 connector. Turn ignition on. Connect a jumper wire between ground and terminal No. 6 (Pink/Black wire) at ECM E8 connector.
  4. With jumper wire connected EGR Vacuum Switching Valve (VSV) is on. Apply air pressure to EGR VSV port "E". Air from port "E" should flow from port "F". See Figure. Disconnect jumper wire. Air from port "E" should not flow from port "F". If EGR VSV operates as specified, check EGR valve. See SYSTEM/COMPONENT TESTS - 2.4L article. Replace EGR valve as necessary. If EGR VSV does not operate as specified, go to next step.
  5. Remove EGR VSV. Using ohmmeter, measure resistance between EGR VSV terminals. Resistance should be 33-39 ohms at 68°F (20°C). Check for continuity between each terminal and body of EGR VSV. If continuity exists, replace EGR VSV. If continuity does not exist, go to next step.
  6. Check EGR VSV operation. Apply battery voltage to EGR VSV terminals. Apply air pressure to EGR VSV port "E". See Figure. Air from port "E" should flow from port "F". Remove battery voltage from EGR VSV terminals. Air from port "E" should not flow from port "F". Replace EGR VSV as necessary. If EGR VSV operates as specified, go to next step.
  7. Check for open circuit in wiring harness between engine compartment fuse block and ECM. See appropriate wiring diagram in WIRING DIAGRAMS - 2.4L article. Repair wiring as necessary. If wiring harness is okay, replace ECM and retest.
scientia non olet · About LEMON Manuals