Water in Fuel Light WIF warning is on.

While on this subject a wire on the WIF sensor has broken on my 2002 313 sprinter. Just changed the filter and noticed it, dont know whether it was already broken or if i broke it today. Will this affect the running of the engine

Aqua Puttana

Poly - Thread Finder
... Will this affect the running of the engine
No. Assuming that it is the WIF sensor wire.

A broken or open wire on a WIF sensor may cause erroneous dash warnings during wet weather. The sensing circuit doesn't know if the water is inside or outside the filter.



A little bit Oooh Errrr
You can drop a silica gel sachet on a string into a tank to absorb water, they will absorb water and leave fuel.
How to get it in the tank is up to you, perhaps added to an inline prefilter?


Engineer In Residence
Silica can only absorb up to 35% of its weight in water (usually less). So a heavily contaminated tank will need quite a bit of desiccant. Better to use a 4 micron filter with silicone water coalescing coating. For vans with an electric lift pump donaldson makes some great filters like this (I have two in series with my engine filter).

Aqua Puttana

Poly - Thread Finder
A recent reminder that, although not an extensive problem, WIF is nothing to be taken lightly.

A friend has a Vito, down on diesel, fills up at a local garage, 100m down the road his vehicle starts to splutter. Has it trayed to his mechanic and $4500 later paid for by his insurance company he is back on the road.

Saw the mixture in a soft drink bottle looked like a lemon drink.

I would have thought his MB Vito would have a water sensor/light.

Our Sprinter has the water sensor stuff under the Fuel filter I wonder if that/light/me, will save the engine, if I get a load of water in the diesel, rather than just a small bit of water over time.

Incidentally the Sprinter Insurance covers dirty Fuel, unlike the RAA with no cover for our Landcruiser ( not that I have ever needed it, but they have accidental damage that does not cover dirty fuel).

My opinion is that we likely do get small amounts of WIF from condensation and slightly off grade fuel, but over time introducing good fresh fuel can help to get rid of those small amounts. The problem is when too much free water is in the fuel tank and it gets pulled into the injection system.


My understanding is that the problems with water in fuel are not so much related to the affects on combustion as they are on the fuel system itself. Particularly the latter end of the fuel system - the injectors and high pressure pump.

These have very tight tolerances and depend on the fuel itself for lubrication. Water, or a water and fuel emulsification, make lousy lubricants. So get too much water (whatever that "too much" is according to the engineers), and you have fuel system problems and failures.
That's my understanding too. In extreme cases water in fuel can even crack injector bodies and nozzles.

That's my discussion here. Water doesn't seem to automatically build up in our tanks. Are we all always getting perfectly dry top quality fuel? That seems pretty doubtful. ALL diesel fuel can carry a bit of water. Some types (biodiesel/blends) can carry more. Temperature affects the water capability. I would expect that the heat/cool cycles that most tanks see would tend to precipitate out the water at one time or other.

The fuel in our Sprinters is heated and circulated back to the tank. The heated fuel will hold more water than cold fuel. Assuming that the fuel we pump into our tank is not very "wet", does that heat and circulation process help to keep the free water from accumulating in our tanks by taking the moisture away in very small doses?

The OEM filter membrane is designed to trap free water. As I mentioned earlier, it must not be trapping the "in range" amount of water in the fuel or else we would all be regularly draining our WIF filter system. Originally "dry" at lower temperature biodiesel when heated may be more efficient at water control than is heated dino diesel.

Granted, sufficient amounts of water in the combustion chamber can cause problems, too.
It would seem to me that the amount of water would need to be pretty high for that to become a real concern. Our WIF monitor should be warning us before that is a problem. I have no data.

Clicking the blue arrow icon within any quote box will take you to the original thread.

Doing that above takes you to more discussion here.

Bio Fuel and Water

Keep Your Fuel Receipts!
Some great advice by Poddydodger. :thumbup::thumbup:
I always pay by card and keep my receipts for a time. I hadn't thought to add the odometer reading on the receipt.

My diesel mechanic advised me to always pay by card, always buy the same brand eg Caltex, BP and always write kms on receipt, this way you have come-back for dirty diesel.

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Aqua Puttana

Poly - Thread Finder
Interesting thread. I own a 2016 Itasca Navion. I read a post saying to buy a Mahle fuel filter.
I have still not found the correct Mahle fuel filter but did see this Mahle article about their fuel-prefilters.

Interesting article. Thanks.

I have read other places that fuel flow and volume inconsistencies create design issues for water separation.

As long as this thread is revived...
Water in fuel doesn't seem to be a great problem here in the USA and, I assume, Canada. I purchased a MAHLE KL 313 filter for my 2006. I have yet to install it.

My advice hasn't changed as to response to a WIF dash warning. The consequences of ignoring water in fuel can be expensive.

It is not a good idea to ignore the WIF warning and just press on.

If the warning isn't caused by some sensor or harness failure and you do have water in your fuel, additives will likely not correct the problem and can increase the extent of damages.

Don't obsess about the possibility of water in diesel fuel. Properly react to a WIF dash warning if it happens.

:2cents: vic


An experienced Mind Parasite.
My :2cents and important detail: the photo is of a 2015 OM 651 fuel filter drain line. I have not extended the drain line so fuel/water will be directed overboard and NOT in engine compartment, but plan to do so.

Splashed/spilled diesel fuel inside the engine compartment is MOOP (Matter Out Of Place) and can contribute to FOD (Foreign Object Damage). A clean engine compartment is a happy place. Especially while performing maintenance or repairs.


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2015 LTV IB: 2015 3500 V6
Pretty sure you can move that line so it drains into a suitable container when bleeding water from the fuel filter.

(so no need to extend the hose... you really want to catch and properly dispose of the water-contaminated fuel you will remove from the hose.)
Just bought my Sprinter on Monday and drove it back home from OH. WIF light came on this morning. On my drive home I fueled up as follows:

-14.960 gallons at Shell in Findlay, OH
-21.710 gallons at BP in Western PA
-12.999 gallons at Sunoco in Eastern PA

Hoping just a drain of the water separator will resolve things.
Just an update: Drained the fuel. WIF light went off. Drove 15-miles home. Fueled up enroute. Light remained off. Parked the rig. This morning I drove it back to work and the WIF light came on again. Power seems normal & no sputtering, etc.
Did you see any water in the drained fuel? Did the fuel look cloudy? If so, you may still have water in the tank. If not, you may have a sensor or wiring issue.
I don't have the drain hose (I guess it was replaced by the dealer from what I have read). Due to this, I basically drained it into some fluid absorbing pads. The light is back off. I'm going to drain some into a large bottle within the next hour or so to check the fuel quality. I'm kind of hoping it's just the sensor wiring at that tight mounting point.

Fuel looks good. No sign of contamination that I can see:


Aqua Puttana

Poly - Thread Finder
Fuel looks good. No sign of contamination that I can see:
It looks good visually to me too.

I suppose that it is possible that the membrane could have separated out some water even in fuel that looks good. I don't know how much water it takes to trigger the dash light.

If all is running well, then maybe it is a harness or other problem that is triggering the warning.

Did you mention the MY of your Sprinter?

:cheers: vic
It looks good visually to me too.

I suppose that it is possible that the membrane could have separated out some water even in fuel that looks good. I don't know how much water it takes to trigger the dash light.

If all is running well, then maybe it is a harness or other problem that is triggering the warning.

Did you mention the MY of your Sprinter?

:cheers: vic
Thanks. I do have it in my sig :) It's a 2010, though the dealership had it listed as a 2011. VIN confirms it's a 2010 per my local MB rep.

I'm going to loosen the wiring mounting location where it's real tight (per other forum posts I've seen) in hopes that this helps resolve it. I'll more than likely change the fuel filter too once I hear back from the dealership confirming they did not change it whilst at their location. I appreciate your two cents!
Just an update: Fuel filter was changed by the dealership from whom I purchased the truck. WIF light came on again yesterday morning. Drove 15-minutes to hike the Appalachian Trail. It was not back on when we got back from the hike 3-hours later.

Aqua Puttana

Poly - Thread Finder
For T1N's. WIF on? Check Fuse #17 under the steering column.


I have done one of the stupid things.

I originally checked all the fuses under the seat but bypassed the under the steering wheel fuse box.
That was a mistake, imagine my surprise when I got to #17 and found it open circuit/blown fuse.
According to the wiring diagram Fuse #17 just happens to control the Engine control Relay, see attached photo.
I chased a lot of red herrings following codes surrounding a lot of our vans quirks.
I skipped a very basic test and wasted a lot of time.
I assumed a lot of things because of the drivability issue (stumbling, misfire) with the WIF light indicator coming on and the CEL also.
The reading i got from the scanner showed a flat reading of 1.6 lbs/min from the MAF even when the van wasn’t running (should have been 0.0) Actual values range up to 24 lbs/min while driving (my numbers never changed from 1.6lbs/min while driving) This had me chasing my tail. (MAF error being one of the codes)
I believe I did have contaminated fuel. During one of the stumbling/misfire events while driving, something blew that fuse.

The error codes were all related to the Engine Control Relay fuse on my 2003 OM612.

I was able to verify that my wiring was in good shape and I cleaned up the wicking fuel in the wiring loom. (Caused by fuel filter draining over the years onto that section of the wiring loom)

The other lesson is that if the WIF sensor is connected outside the filter, the light should be out. There’s no water to make the connection. (Barring a shorted circuit)

I am happy the problem is resolved and back to code free driving. Thanks for the input.

:cheers: vic

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