Diagnostic Procedures

Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.

NOTE: If DTC P0403 or DTC P0405 are set, diagnose those DTCs first. See DTC P0403: EGR SOLENOID CONTROL CIRCUIT or DTC P0405: EGR SENSOR CIRCUIT LOW VOLTAGE .

Install a scan tool. Turn ON the ignition. Use a scan tool in order to command the EGR valve from 0 percent to 100 percent. Does the EGR position sensor remain within 15 percent of the Desired EGR Position at all commanded positions? If yes, go to next step. If no, go to step 4.
Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Operate the vehicle within the Conditions for Running DTC, or within the parameters observed in the Freeze Frame/Failure Records. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
Turn OFF the ignition. Disconnect the EGR valve. Turn ON the ignition, with the engine OFF. Use a scan tool in order to observe the EGR position sensor parameter. Does the scan tool indicate that the EGR Position Sensor is at 0 percent? If yes, go to next step. If no, go to step 8.
Measure the voltage from the 5-volt reference circuit of the EGR position sensor to the ground circuit of the EGR position sensor. Does the DMM display voltage near 5 V? If yes, go to next step. If no, go to step 7.

NOTE: If the fuse blows, locate and repair a short to ground in the signal circuit.

Connect a fused jumper between the 5-volt reference circuit of the EGR position sensor and the EGR pintle position signal circuit of the EGR position sensor. Does the scan tool indicate that the EGR Position Sensor is near 100 percent? If yes, go to step 12. If no, go to step 10.
Measure the voltage from the 5-volt reference circuit of the EGR position sensor to a good ground. Does the DMM display voltage near 5 V? If yes, go to step 9. If no, go to step 11.
Test the EGR pintle position signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 16. If no, go to step 13.
Test the EGR position sensor ground circuit for an open or for high resistance. Did you find and correct the condition? If yes, go to step 16. If no, go to step 13.
Test the signal circuit for high resistance or a high resistance short to ground. Did you find and correct the condition? If yes, go to step 16. If no, go to step 14.
Test the 5-volt reference circuit of the EGR position sensor for an open, for a short to ground, or for a short to voltage. Did you find and correct the condition? If yes, go to step 16. If no, go to step 14.
Inspect for poor connections at the harness connector of the EGR valve. Did you find and correct the condition? If yes, go to step 16. If no, go to step 14.
Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step 16. If no, go to step 15.
Replace the EGR valve. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 16.
Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step 2.
Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.