I have a P0405 code which is "Exhaust Gas Recirculation Sensor A Circuit Low" when the engine is cool and the ERG is not operating. After the engine warms up and the EGR valve is operating sometime the code changes to P0401. I have checked the EGR valve/soleniod and it appears to be operating OK. This is from an 05 Hemi. Has anyone got any idea what else could cause that error code? Does anyone know what voltage should be coming out of the ERG unit back to the PCM?

 

Yup,

Two things.
1. Make sure the gas cap is tight
2. Check the condition of the rubber hoses that connect the lines to the charchol canister.

If they are cracked or checked at all, replace them. This has been a common DTC with many of the "few" years old rams. If its under warranty yet, have the dealership do it. I had the same problems with mine but it turned out to be the wire that fires the solenoid rubbing on one of the front end components (< not common). most often its the rubber connection lines at the canister

 

I would have never associated an error with the EGR with leaks in the fuel system. I'll explore it.

 

mbennett6,
I got my wires crossed up when I looked up the DTC code. There is a sweep (variable resistor) in the EGR that lets the computer know its position. Most likely the feedback info is incorrect. You might try pulling the connector and cleaning them good first. If after that the DTC continues to come up, replace the EGR valve