DTC Troubleshooting: P0406 (12)

DTC P0406:  EGR Valve Position Sensor Circuit High Voltage


1.Turn the ignition switch ON (II).

2.Check the EGR VLS in the DATA LIST with the Honda PGM tester or the HDS.

Is 4.88 V or higher indicated?


YES - Go to 3.


NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the EGR valve and the  ECM/PCM.n


3.Turn the ignition switch OFF.

4.Disconnect the EGR valve 6P connector.

5.Turn the ignition switch ON (II).

6.Measure voltage between EGR valve 6P connector terminals No. 2 and No. 3.

Is there about 5 V?


YES - Go to 8.


NO - Go to 7.


7.Measure voltage between ECM/PCM connector terminals A20 and A23.

Is there about 5 V?


YES - Repair open in the wire between the EGR valve and the ECM/PCM (A23), then go to 10.


NO - Go to 14.


8.Turn the ignition switch OFF.

9.Replace the EGR valve.

10.Turn the ignition switch ON (II).

11.Do the ECM/PCM RESET in the CLEAR MENU with the Honda PGM tester or the HDS.

12.Do the ECM/PCM idle learn procedure.

13.Check for Temporary DTCs or DTCs in the DTCs MENU with the Honda PGM tester or the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P0406 is indicated, check for poor connections or loose terminals at the EGR valve and the  ECM/PCM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC troubleshooting.


NO - Troubleshooting is complete.n


14.Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.

15.Check for Temporary DTCs or DTCs in the DTCs MENU with the Honda PGM tester or the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P0406 is indicated, check for poor connections or loose terminals at the EGR valve and the  ECM/PCM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC troubleshooting.


NO - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM.n