DTC Troubleshooting
Control System DTCs
DTC Troubleshooting: P0404
DTC P0404 : EGR Valve Circuit Range/Performance Problem
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information How To Troubleshoot The Fuel And Emissions Systems.
1. Problem verification:
Problem verification
-1. Turn the ignition switch to ON (II).
-2. Clear the DTC with the HDS.
-3. Start the engine. Hold the engine speed at 3,000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
-4. Do the EGR TEST with the HDS.
Is the result OK?
-YES- Intermittent failure, the system is OK at this time. Clean any carbon build-up on the EGR valve with throttle plate cleaner.
-NO- Failure is duplicated. Go to step 2.
2. EGR valve position sensor internal circuit check:
EGR valve position sensor internal circuit check
-1. Turn the ignition switch to LOCK (0).
-2. Disconnect the following connector.
-3. At the EGR valve side, measure the resistance between test points 1 and 2.
Is there 100 kOhms or more?
-YES- Replace the EGR valve Service and Repair, then do the repair verification.
-NO- Go to step 3.
3. EGR valve internal circuit check:
EGR valve internal circuit check
-1. At the EGR valve side, measure the resistance between test point 1 and 2.
Is there 100 kOhms or more?
-YES- Replace the EGR valve Service and Repair, then do the repair verification.
-NO- Go to step 4.
4. Open wire check (PG line):
Open wire check (PG line)
-1. Check for continuity between test point 1 and 2.
Is there continuity?
-YES- The PG wire is OK. Go to step 5.
-NO- Repair an open in the PG wire between the EGR valve and G101, then do the repair verification.
5. Shorted wire check (E_EGR line):
Shorted wire check (E_EGR line)
-1. Jump the SCS line with the HDS.
-2. Disconnect the following connector.
-3. Check for continuity between test points 1 and 2.
Is there continuity?
-YES- Repair a short in the E_EGR wire between the ECM/PCM (B2) and the EGR valve, then do the repair verification.
-NO- The E_EGR wire is not shorted. Go to step 6.
6. Open wire check (E_EGR line):
Open wire check (E_EGR line)
-1. Check for continuity between test points 1 and 2.
Is there continuity?
-YES- The E_EGR wire is OK. Go to step 7.
-NO- Repair an open in the E_EGR wire between the ECM/PCM (B2) and the EGR valve, then do the repair verification.
7. EGR port and passage cleaning:
EGR port and passage cleaning
-1. Remove the EGR valve. Service and Repair
-2. Clean the intake manifold EGR port with throttle plate cleaner. Also, clean the passage inside the EGR valve with throttle plate cleaner.
-3. Install the EGR valve. Service and Repair
-4. Reconnect all connectors.
-5. Turn the ignition switch to ON (II).
-6. Reset the ECM/PCM with the HDS How To Troubleshoot The Fuel And Emissions Systems.
-7. Do the ECM/PCM idle learn procedure. ECM/PCM Idle Learn Procedure
-8. Do the EGR TEST with the HDS.
Is the result OK?
-YES- The failure is not duplicated. Do the repair verification.
-NO- Go to step 8.
8. EGR valve check (substitution):
EGR valve check (substitution)
-1. Substitute a known-good EGR valve.
-2. Reconnect the EGR valve 5P connector.
-3. Turn the ignition switch to ON (II).
-4. Reset the ECM/PCM with the HDS How To Troubleshoot The Fuel And Emissions Systems.
-5. Do the ECM/PCM idle learn procedure. ECM/PCM Idle Learn Procedure
-6. Do the EGR TEST with the HDS.
Is the result OK?
-YES- Replace the original EGR valve Service and Repair, then do the repair verification.
-NO- The EGR valve is OK. Update the ECM/PCM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM/PCM Service and Repair, then do the repair verification.
Repair verification (OBD STATUS check):
-1. Turn the ignition switch to LOCK (0).
-2. Reconnect all connectors.
-3. Turn the ignition switch to ON (II).
-4. Reset the ECM/PCM with the HDS How To Troubleshoot The Fuel And Emissions Systems.
-5. Do the ECM/PCM idle learn procedure ECM/PCM Idle Learn Procedure.
-6. Do the EGR TEST with the HDS.
-7. Monitor the OBD STATUS for DTC P0404 with the HDS.
Does the HDS indicate PASSED, FAILED, EXECUTING, or OUT OF CONDITION?
-PASSED- Troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM Service and Repair. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.
-FAILED- Go to step 1 and recheck. If the ECM/PCM was updated, substitute a known-good ECM/PCM Service and Repair, then check the OBD STATUS again.
-EXECUTING- Keep the test condition until a result comes on.
-OUT OF CONDITION- Meet the test condition, and check the OBD STATUS again.