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DTC P0400: EGR Function: Procedure

  1. Check exhaust system for leaks. Repair as necessary. If no leaks are found, start engine and warm to normal operating temperature. Disconnect vacuum hose from EGR valve. Check for vacuum at hose. Vacuum should not exist at idle. Check for vacuum while quickly increasing engine speed to 3000 RPM. Vacuum should exist while increasing engine speed. If vacuum is as specified, go to next step. If vacuum is not as specified, go to step  3.
  2. Turn ignition off. Remove EGR valve. Using a hand vacuum pump, apply vacuum to EGR valve. EGR valve should open. If EGR valve opens, test is complete. If EGR valve does not open, check for sticking and clean or repair as necessary. Replace EGR valve, if it is not sticking.
  3. Inspect vacuum hose for blockage, leak or poor connection. Repair as necessary. If vacuum hose is okay, turn ignition off. Disconnect ECM harness connector. See Figure. Turn ignition on. Connect a jumper wire between ground and ECM harness connector terminal No. 103. See Figure. Listen for EGRC solenoid operating sound while disconnecting and connecting jumper wire. If operating sound is heard, go to next step. If operating sound is not heard, repair EGRC solenoid or circuit. See DTC P1400: EGR CONTROL (EGRC) SOLENOID .
  4. Check EGRC solenoid. See DTC P1400: EGR CONTROL (EGRC) SOLENOID . Replace, if necessary. If EGRC solenoid is okay, check EGRC-BPT. See DTC P0402: EGR CONTROL BACKPRESSURE TRANSDUCER (EGRC-BPT) . Replace, if necessary. If EGRC-BPT is okay, check EGR temperature sensor. See DTC P1401: EGR TEMPERATURE SENSOR . Replace, if necessary. If EGR temperature sensor is okay, go to next step.
  5. No problem is currently indicated. Problem may be intermittent. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article.
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