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Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Disconnect EGR temperature sensor. EGR temperature sensor is mounted on EGR valve body. Using ohmmeter, measure resistance between sensor terminals. If resistance is 600,000 ohms or less, go to next step. If resistance is more than 600,000 ohms, check sensor. See SYSTEM/COMPONENT TESTS - 3.4L article. Replace as necessary.
  2. Turn ignition on. Using DVOM, measure voltage between sensor wiring harness connector terminals. If voltage is 4.5-5.5 volts, go to step 4). If voltage is not 4.5-5.5 volts, go to next step.
  3. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe connector. On A/T models, measure voltage between terminal No. 21 (Pink/Green wire) and No. 22 (Brown/Black wire) at ECM E7 connector. See Figure or Figure. On M/T models, measure voltage between terminals No. 9 (Brown/Black wire) and No. 14 (Pink/Green wire) at ECM E7 connector. On all models, if voltage is 4.5-5.5 volts, check for open circuit in wiring harness between EGR temperature sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS - 3.4L article. Repair wiring as necessary. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  4. Check all EGR system vacuum hoses. Replace vacuum hoses as necessary. If EGR vacuum hoses are okay, access ECM behind glove box. Ensure ignition is off. Disconnect ECM E6 connector (A/T models) or E8 connector (M/T models). Turn ignition on. On A/T models, connect a jumper wire between ground and terminal No. 8 (Red/White wire) at ECM E6 connector. On M/T models, connect a jumper wire between ground and terminal No. 18 (Red/White wire) at ECM E8 connector.
  5. With jumper wire connected, EGR Vacuum Switching Valve (VSV) is on. Apply air pressure to EGR VSV port "E". See Figure. Air from port "E" should flow from small filter on end of EGR VSV. Disconnect jumper wire. Air from port "E" should flow from port "G". If EGR VSV operates as specified, go to step 8). If EGR VSV does not operate as specified, go to next step.
  6. Turn ignition off. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 33-39 ohms at 68°F (20°C). Measure resistance between each terminal and body of EGR VSV. Resistance should be infinite. If resistance is not as specified, replace EGR VSV. If resistance is as specified, go to next step.
  7. 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 small filter on end of EGR VSV. Remove battery voltage from valve terminals. Air from port "E" should flow from port "G". Replace EGR VSV as necessary. If EGR VSV operates as specified, check for open circuit in wiring harness between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS - 3.4L article. Repair wiring as necessary.
  8. Check EGR vacuum modulator. See SYSTEM/COMPONENT TESTS - 3.4L article. Replace EGR vacuum modulator as necessary. If EGR vacuum modulator is okay, check EGR valve. See SYSTEM/COMPONENT TESTS - 3.4L article. Replace EGR valve as necessary. If components are okay, go to next step.
  9. Disconnect EGR temperature sensor connector. Start engine. Ensure engine is at normal operating temperature. Disconnect EGR VSV connector. Run engine at 4000 RPM for 3 minutes and measure resistance between EGR temperature sensor terminals. If resistance is 4300 ohms or less, replace ECM and retest. If resistance is more than 4300 ohms, replace EGR temperature sensor.
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