Water in the DPFE Sensor '96 Ranger 3.0L

RgerBob · May 22, 2015

DPFE was reporting a P0401 code and replaced it and ran for a couple of months w/o the code but then one morning it came back on. Drove it for months until I had time and warmer weather, when I pulled it off, I found water drops out which I could imagine would be the cause off the insufficient airflow code from the sensor. Took the water out and put back the same sensor, of course the code came back after a week. Checking there was water back in there again - glad I didn't put a new sensor in. Where do you think the water comes from? I drive 20-40 miles and make it to 60mph at least a quarter of the time - I've read short trips can cause condensation but I'm about 10 miles from anything.

BTW - I just change the hoses to the sensor with those nice looking ones with the red liner - much tighter fit than the hoses that I replaced the last time. At the truck's old age, it could be anything I suppose. I have a new DPFE sensor sitting in the box but don't want to put it in until the water issue is resolved, ..unfortunately the truck needs to pass inspection within the month.
96' Ranger 6cyl3.0l 180k great truck.
Thanks for your time and any feedback.

RgerBob · May 26, 2015

No replies so I guess I stumped everyone. I'm throwing in the towel, it's going into the dealer tomorrow. Should be interesting bringing in a 19 yr. old truck, just hope they don't break anything trying to fix it. :icon_confused:

Earl43P · May 27, 2015

It is normal to have moisture in there.
Unfortunately, that tends to create deposits on the face of the DPFE Diaphragm and it will eventually put out an erroneous feedback signal as a result.

Dealer is simply going to drain your wallet on this job. DPFE failure is quite common and the aftermarket plastic ones typically have a one year warranty, which I have used. My commute used to be 4 miles, so I had lots of moisture in there too and replaced several DPFEs.

Start reading all about EGR at the following link:

http://www.tomco-inc.com/techinfo.html

RonD · May 27, 2015

When you burn hydrocarbons(h) with oxygen(o) one of the byproducts is h2o(water) so exhaust will always have water content, this is why exhaust systems rust from the inside out.

The water in the exhaust is a vapor, warmer air can hold more water vapor than colder air.
As the warm exhaust air travels down the exhaust system it is cooled and can not hold as much water vapor so the water condenses out and you often see the water dripping from tail pipe.

When you shut off the engine the water vapor will start to condense on cooler parts first.
Common example is when you have a cold glass of your favorite beverage on a hot day, the glass will get wet on the outside.
As the warm air comes in contact with the cold glass it cools so can't hold water vapor and leaves its water vapor on the glass, same thing happens on windshield in cold weather, warmer air in the cab comes in contact with colder glass and deposits it water vapor.

So the reason you get water in the DPFE is because it is cooler than the exhaust air.
Now the DPFE sensor hoses are not pass thrus, the air doesn't circulate which is why there is a build up over time, warm air rises so there will be some air exchange which is where the water comes from.
Metal DPFE sensors would tend to hold heat longer so less condensation but not none.
Since this is a pressure system not a circulation system you could install longer hoses that had a loop down then up, a water trap of sorts, but also stopping the warm air rising circulation.

Water in the DPFE Sensor '96 Ranger 3.0L

RgerBob

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