Diagnostic Aids

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Monitor EGR actual position display while moving EGR connections and related harnesses. Change in scan tool display will indicate area of fault. Check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORD DATA. Operate vehicle within conditions noted in FAILED RECORDS DATA. Read SPECIFIC DTC. If scan tool displays DTC P1404 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1404 FAILED THIS IGN, check for an intermittent problem, see DIAGNOSTIC AIDS  .
3. Turn ignition off. Disconnect EGR valve harness connector. Inspect EGR valve and connector for damaged pins or terminals. Repair as necessary. If EGR valve and connector pins or terminals are okay, go to next step.
4. Remove EGR valve. Check EGR valve for excessive carbon deposits on EGR shaft. Check for foreign material inside EGR valve. If excessive carbon is found, go to next step. If excessive carbon is not found, go to step 6).
5. Clean EGR valve shaft and inside EGR. Remove foreign material from EGR valve. Check for damage of pintle and seat. If severe damage is present, replace EGR valve. If damage is not present, go to next step.
6. Reinstall EGR valve. Install scan tool. Start and run engine at idle. Using scan tool, check EGR operation by using UP arrow to increase EGR from zero percent to 40 percent. If EGR operates, system is okay. If EGR does not operate, go to next step.
7. Using scan tool, reset EGR valve position. Repeat test in step 7). If EGR operates, system is okay. If EGR does not operate, replace EGR valve. If system still does not operate after replacement of EGR, replace PCM.