I am having an issue resolving a P0406 on a 2010 Town and Country

Resolved all other powertrain codes.

Followed Chrysler Diagnostic tree and everything checked out.

Replaced EGR valve and checked EGR for flow.

Voltage sense reading close to 5V on scan tool, but only 2 to 3 V on the back-probe.

Checked and cleaned all sensor connections on top of engine.

It's crunch time. Inspection appointment is on 31st.

I am just wondering if anyone here with experience with these Minivans has any ideas that may help me pinpoint the issue.

Regards,

epizoan

 

cheap part will get wrong feed back to the PCM

 

I wouldn't call a Chrysler OE EGR valve a cheap part by any means. Lol.

 

3.3 3.8 or 4.0 engine? where did you get this OEM Egr from? Dealer likely would not stock a 14 year old part.

 

3.8

My local Chrysler dealer. You would be surprised what the dealer networks can come up with... I only use OE or top-shelf aftermarket when it comes to engine sensors on late model vehicles. Too many bad experiences with poor quality sensors causing havok.

Issue seems to be resolving. I popped off the back of the connector and found moisture under the weather seal. Cleaned it out and fully dried it. Previous owner had a pinhole coolant leak in the heater hose between the Y pipe and water outlet, as well as a few loose hose clamps that dumped coolant all over the left side of the engine bay. He drove it and just kept topping off the coolant rather than having the issue repaired. I found a few other coolant logged connectors in that area and took care of them as well. MIL is off although code is still stored. Sense voltage is still reading on scan-tool in the upper 4V range at idle. EGR seems to be functioning as designed. I did chase down the EGR ground today, just to make sure that it was solid and it wasn't trying to ground through sensor ground and skewing voltages. Going to be going on a short trip tomorrow. A couple of hours on the highway and some City driving should be enough to determine if the issue will be pervasive.

I am not entirely convinced that this will be the end of it though. There are a few other electrical issues that I have to track down and repair, including the common CAN short in the driver's door.

The one that perplexes me... Occasionally the instrument cluster will light up with all the warning lights and then they will begin to flicker. Just the instrument panel, nothing else. I believe it may have something to do with the CAN short in the driver's door, but the flickering of the lights (dim-bright, not on-off) doesn't make sense to me.

 

RESOLUTION

I wanted to give it some time before I posted the resolution to this issue to be sure that it was actually fixed.

The main body ground (under the battery tray on the frame) connects both the negative terminal and the EGR ground. Although the ground connection was tight it was not making a solid connection. Once removed and cleaned the ground connection and reattached the grounds, both issues disappeared.

The body ground was causing the issues with voltage drop and the instrument panel going wonky, and (my hypothesis) the EGR ground having a bad connection was forcing the EGR valve to fault to SENSOR GROUND which was causing the EGR HIGH circuit issue.