DTC P0404 (6-Speed A/T, 16-18 9-Speed A/T)

DTC P0404  : EGR Valve Circuit Range/Performance Problem

NOTE:  Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Fuel and Emissions Systems .

DTC (PGM-FI)

1. Problem verification

   - 1. Turn the vehicle to the ON mode.

   - 2. Clear the DTC with the HDS.

   - 3. Start the engine.

   - 4. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.

   - 5. Do the EGR TEST with the HDS.

   EGR TEST

   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. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot - Refer to: How to Troubleshoot the Fuel and Emissions Systems .

   NO 

   Failure is duplicated. Go to step 2.

2. EGR valve position sensor internal circuit check

   - 1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the following connector.

   EGR valve 5P connector

   - 3. At the EGR valve side, measure the resistance between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	EGR valve 5P connector: disconnected
   Test point 1	EGR valve 5P connector No. 3 (EGR valve side)
   Test point 2	EGR valve 5P connector No. 4 (EGR valve side)

   Courtesy of HONDA, U.S.A., INC.

   Is there 100 kΩ or more?

   YES 

   Replace the EGR valve .

   NO 

   Go to step 3.

3. EGR valve internal circuit check

   - 1. At the EGR valve side, measure the resistance between test point 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	EGR valve 5P connector: disconnected
   Test point 1	EGR valve 5P connector No. 2 (EGR valve side)
   Test point 2	EGR valve 5P connector No. 4 (EGR valve side)

   Courtesy of HONDA, U.S.A., INC.

   Is there 100 kΩ or more?

   YES 

   Replace the EGR valve .

   NO 

   Go to step 4.

4. Open wire check (E-EGR PG/PG line)

   - 1. Check for continuity between test point 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	EGR valve 5P connector: disconnected
   Test point 1	EGR valve 5P connector No. 1
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The E-EGR PG/PG wire is OK. Go to step 5.

   NO 

   Repair an open in the E-EGR PG/PG wire between the EGR valve and G101.

5. Shorted wire check (E EGR line)

   - 1. Jump the SCS line with the HDS, and wait more than 1 minute.

   - 2. Disconnect the following connector.

   PCM connector C (51P)

   - 3. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	EGR valve 5P connector: disconnected
   	PCM connector C (51P): disconnected
   Test point 1	PCM connector C (51P) No. 13 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2016 2017 2018), or PCM Connector for Inputs and Outputs(6-Speed A/T) (2016 2017 2018 2019 2020)
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short in the E EGR wire between the PCM (C13) and the EGR valve.

   NO 

   The E EGR wire is not shorted. Go to step 6.

6. Open wire check (E EGR line)

   - 1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	EGR valve 5P connector: disconnected
   	PCM connector C (51P): disconnected
   Test point 1	EGR valve 5P connector No. 5
   Test point 2	PCM connector C (51P) No. 13 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2016 2017 2018), or PCM Connector for Inputs and Outputs(6-Speed A/T) (2016 2017 2018 2019 2020)

   Courtesy of HONDA, U.S.A., INC.

   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 PCM (C13) and the EGR valve.

7. EGR port and passage cleaning

   - 1. Remove the EGR valve.

   - 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.

   - 4. Reconnect all connectors.

   - 5. Turn the vehicle to the ON mode.

   - 6. Reset the PCM with the HDS.

   Reset PCM

   - 7. Do the PCM idle learn procedure.

   - 8. Do the EGR TEST with the HDS.

   EGR TEST

   Is the result OK?

   YES 

   The failure is not duplicated.

   NO 

   Go to step 8.

8. EGR valve check (substitution)

   - 1. Substitute a known-good EGR valve.

   - 2. Reconnect the following connector.

   EGR valve 5P connector

   - 3. Turn the vehicle to the ON mode.

   - 4. Reset the PCM with the HDS.

   Reset PCM

   - 5. Do the PCM idle learn procedure.

   - 6. Do the EGR TEST with the HDS.

   EGR TEST

   Is the result OK?

   YES 

   Replace the original EGR valve .

   NO 

   The EGR valve is OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or substitute a known-good PCM - Refer to: PCM Removal and Installation (6-Speed A/T), ('16-'18 9-Speed A/T) .