Just pulled in the drive way from a 2.5 hour highway trip and the water separator light came on for 10 seconds and then turned off.
The CRD had it's 25K mile service last month and the fuel separator was changed. I also have a locking fuel cap to deter thieves and pranksters. I have been purchasing fuel at the same truck stop for a year now without any issues as well.
So,
Has anyone had the fuel separator light come on for a few seconds and then turn off, or does it just stay on when it senses water in the fuel filter/separator?

First, feel down under the fuel filter where the water-in-filter sensor is mounted and see if it's in tight, I think it screws into the bottom. Maybe run a bottle of PowerService 911 through the tank with new fuel. The light should stay on, so..... ???

Did you try to drain it yet? Thinking with all the rain in the past week maybe got some contaminated fuel, may not even be the retailer's fault. The reason I mention this is at work we have a fleet of smaller buses with the same filter/sensor set-up. I took several calls in the past 3 days for the same thing which is unusual. I think we got some contaminated fuel in the past week. I would see if you get any water out of the drainage fluid (drain it into a glass and let it rest/separate). Try some Power Service to dry it out first with the old filter. Afterwards, you will probably have to replace the filter again.

In my last post, the Water Separator Warning Light was intermittently on and off but that was a disguise that "Libby" was throwing my way. However, this now appears to not point to the fuel filter. As of today at 25K miles, the transmission torque converter is reluctantly downshifting to the point where coming to a stop feels like your running over rumble strips on the highway. Oh, and yes the usual 35 mph muted lug is now more present than ever.
The engine is clattering much louder than usual at idle and it's clatter is not consistent. "Libby" started smoking A LOT today, almost a two packer and there is severe turbo lag.
Oh, and did I mention the Water Separator Warning light playing hide and seek on my instrument panel in the midst of all this?

IMHO, the TCM seems to be causing spurious signals to the ECM which is triggering the the on and off state of the Water Separator Warning Light. No error codes have been thrown.

Diesel Tech at the dealership said that he wants to get this thing fixed correctly. He also agrees that it's not water in the fuel. As of this morning, he will start with a littany of process of elimination steps.
1) Hook ECM and TCM to DRB and check all map values
2) Order new EGR flow control valve
3) Pull Intercooler and either clean or order a new one
4) Take fuel sample
5)???
6)???
At least the dealership was immediately on the ready with a loaner.

Stay tuned..............

If you get a chance to talk to the tech or watch the work, still want to know how the intercooler is removed.

Recently I've seen two reports of wires in a position to get chaffed/cut. On my January 06 there's a wire bundle rubbing a sharp edge on the plate the fuel filter is mounted on. Earlier ones have the wire bundle lower where the bracket has a rolled edge to protect it. Another posted about a wire bundle down under the left side of the engine somewhere but I've not looked there yet.

DCX instructed the tech to replace the torque converter and the front pump in the transmission.

Just pulled in the drive way from a 2.5 hour highway trip and the water separator light came on for 10 seconds and then turned off.
The CRD had it's 25K mile service last month and the fuel separator was changed. I also have a locking fuel cap to deter thieves and pranksters. I have been purchasing fuel at the same truck stop for a year now without any issues as well.
So,
Has anyone had the fuel separator light come on for a few seconds and then turn off, or does it just stay on when it senses water in the fuel filter/separator?

In my last post, the Water Separator Warning Light was intermittently on and off but that was a disguise that "Libby" was throwing my way. However, this now appears to not point to the fuel filter. As of today at 25K miles, the transmission torque converter is reluctantly downshifting to the point where coming to a stop feels like your running over rumble strips on the highway.

Were talking about the Water/Fuel Seperator cannister under the hood right? I have a new one that needs to be installed because I'm at 27.5K miles. Is this easy to change out? I was hoping to do it myself. I have a guy that is going to change the two trannie filters after dropping the pan. I'm replacing the old fluid with AM SOIL synthetic fluid. Any idea on how manny quarts I am going to need for the trannie oil pan?