DTC Troubleshooting: P0406 (12-5)

DTC P0406 (12-5):  EGR Valve Position Sensor Circuit High Voltage

1.Reset the ECM/PCM.

2.Start the engine.

Is DTC P0406 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 at 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 the EGR valve 6P connector terminals No. 2 and No. 3.


Is there about 5 V?

YES - Replace the EGR valve.n

NO - Go to 7.

7.Measure voltage between ECM/PCM connector terminals A10 and A20.


Is there about 5 V?

YES - Repair open in the wire between the EGR valve and the ECM/PCM (A10).n

NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original  ECM/ PCM.n