Chrysler Repair: Code P0405: egr sensor voltage low, egr sensor, egr valve

Question
I just purchased an 05 grand caravan. I live in Ontario so there might be small differences in the emissions equipment. The cel light was on when I bought it. The car lots big chrysler scanner said low egr (p0405) Had the egr replaced with a mopar one and the computer was reset. 100 feet out of the lot the lights back on with the same code. I have seen talk on the internet about checking vac leaks in the rubber hose coming from the egr, however mine only has 1 metal tube running from the egr to the top of the engine. Where else would I look for the trouble? Also it can be very hesitant if I touch the gas very lightly from a standstill. The engine chugs abit like a bad driver with a stick shift and the rpms bounce up and down, almost stalling the engine. Not sure if the 2 are related. Put brand new bosch plugs in to no avail.

Answer
Hi Jamie,
The egr on the engine probably has an electic solenoid control witha position sensor, along with the vacuum actuation. I don't have the '05 manual but an earlier manual shows that if you do, the plug at the solenoid would have 6 pins (but only 5 wires). The the light green/pink wire on pin 1 is the signal wire and it should be greater than 0.17 volts and less than 4.9 volts (It has a 5 volt supply on the violet/white wire, if that is OK. If missing, that would be the cause of the problem). It has a 12 volt supply on the orange/dark green wire, with the engine running.
The black/light blue wire is a ground wire for the signal measurement. Finally the gray/yellow controls the solenoid valve operation. Any of those wires could be shorted and cause the code or 'open and cause the code. So unplug it and check for short to ground or open with the plugs at the pcm also disconnected.
In the order that I listed you would find them connected to: pin 34 of the pcm, pin 62 of the pcm, pin 34 of the pcm, the ASD relay output, pin 43 of the pcm, pin 40 of the pcm.
The symptom you describe is likely to be related to the egr valve being ajar slightly at idle. Whether it is mechanical or electrical needs to be determined, but because it is a new valve I would pursue the wiring issues I listed above.
Roland
PS I can't be certain about the pin assignments because I don't have an '05 manual, but the color codes are likely correct and the expected voltages too.