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Discussion Starter · #1 ·
Hi There. I just replaced the fuel filter, WIF sensor, and fuel filter head assembly on my 05 LLY. I replaced the filter head assembly because the threads were leaking and air bubbles were coming out of there. Once I replaced that, there were no more air bubbles or leaks so I thought that had fixed the issue. But then when I started it back up after the replacement for the first time in a week, I am getting the water in fuel message on the dash and it's not going away. I don't think it's the WIF sensor because it's brand new. And I don't see why there would be any water in the filter since it's brand new as well. I am at a 1/2 tank, and before the replacement I didn't get the message either. I am not sure if it's some sort of glitch, or if there is actually water in the fuel tank. Any idea or experiences? Any suggestions are appreciated. Thank you
 

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You properly bled the air from the filter/system after installing the new assembly? Even though that WIF sensor is brand new, that's the only place (I think) where that message could be coming from. Check the electrical harness and make sure it's seated properly and no pins are bent or anything (i.e. good connection). If all that looks good I'd swap out the new WIF sensor in case you got a dud.
 

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Discussion Starter · #3 ·
You properly bled the air from the filter/system after installing the new assembly? Even though that WIF sensor is brand new, that's the only place (I think) where that message could be coming from. Check the electrical harness and make sure it's seated properly and no pins are bent or anything (i.e. good connection). If all that looks good I'd swap out the new WIF sensor in case you got a dud.
Yes bled the air out of bleeder screw until only fuel was coming out of it. I made sure no leaks were coming out of the inlet and outlet fuel lines either. The truck ran fine but the water in fuel message has never come on before which scares me lol. I will maybe try to unplug the WIF sensor wires from the harness and plug them back in. Should I wait and drive it until I need to refuel again to see if it continues to do it with a fresh tank of diesel? Or should I try to take off the WIF sensor again (3rd time 🤦‍♂️ lol) and drain the fuel out of the filter. What do you think my best bet is? Thank you
 

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I'm no expert so perhaps some others will jump in... but it sounds like the sensor is shooting out a false reading, if you're sure the fuel isn't contaminated. If so, then yes maybe run the fuel down some more, fill with fresh, and see if the warning message continues. If it does at that point, to me that would point to a faulty sensor.
 

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Discussion Starter · #5 ·
I'm no expert so perhaps some others will jump in... but it sounds like the sensor is shooting out a false reading, if you're sure the fuel isn't contaminated. If so, then yes maybe run the fuel down some more, fill with fresh, and see if the warning message continues. If it does at that point, to me that would point to a faulty sensor.
Okay that makes sense. Got the sensor from NAPA and not from GM. Hopefully I can explain the situation to NAPA and see if they will give me a new one for free. Thanks for the help.
 

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I have a friend that went thru this as well. Long story short, replaced with gm and no longer has had any issues.

Save yourself the headache, get the refund and go buy gm... OR delete the damn thing. Like you said, I have never seen a wif msg before.
 

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There shouldn't be much explaining you need to do with NAPA. Tell them the sensor is defective and giving a bad reading. Since it's been installed they may not refund but I'm sure it's under warranty to get a replacement to at least try.

These trucks do seem pretty sensitive to aftermarket parts from what I've read.
 

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As I recall, if the WIF connector is disconnected, then it should not have the WIF alarm. So, disconnect it and see if the problem goes away. If it goes away, bad sensor. If it doesn't go away, then there is some other wiring problem (pinched/shorted somewhere while working on it?).
 
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Did you actually open the drain on the WIF sensor to verify that there's no water in the fuel?
 

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Did you actually open the drain on the WIF sensor to verify that there's no water in the fuel?
I was going to ask this as well. Before you start assuming it's malfunctioning, you better make sure the old one wasn't malfunctioning and not providing a reading it should have been.

Open the drain on the bottom of the WIF sensor and see if any water comes out.
 

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Discussion Starter · #11 ·
Okay will open the drain on the bottom of the WIF sensor. Should fuel come out of the bottom as well or only water?
 

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Both, best to attach a hose to it and drain in a clear bottle so you can see if it has water in it.
 

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Discussion Starter · #13 ·
Okay drained the water and fuel out of the WIF sensor drain plug. Going to start it back up to see if the message still pops up. But do I need to reprime the filter before start up?
 

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Yes, prime the filter.

Was there any fuel/water separation in what you drained from the filter? (If you used a clear bottle and can see what came out.)
 

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Discussion Starter · #15 ·
Yes I used a clear bottle but didn't get all of the sample amount possible. It was hard to reach down there with the bottle. Yes there's a tiny bit of discoloration in the fuel but it doesn't look like there's any clear separation of fuel and water. But that could be from the little amount I collected. I tried unplugging the sensor wires to see if the message would go away and it did. Then I plugged the harness back in and up came the WIF message. Not sure if I could try to collect more of a sample or should I let this sample sit awhile longer.
 

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Discussion Starter · #16 ·
Should I drive it around a bit to get the sensor to fill up again and get a smaller bottle down there to collect a sample? How long does it take for the water to completely separate?
 

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Discussion Starter · #17 ·
1082989


Hey there again, so these are the two samples I got out of my truck yesterday evening. The one on the left is the 1st one, and the one on the right is the 2nd one I got. This photo was taken roughly 20 hours after the samples were collected. I dont see any water separation from either of them (the one on the right seems clearly but it's just the photo, it seems to be 100% diesel fuel in that container). Do you guys agree? It has to be the dud of a sensor I am assuming then? Let me know. Thank you!
 

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Can't really tell from the photos, I would've caught some more in the bottles but you could very well have a bad WIF sensor. Just didn't want you to come to that conclusion without making sure that there was no water there first.
 

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Hi There. I just replaced the fuel filter, WIF sensor, and fuel filter head assembly on my 05 LLY. I replaced the filter head assembly because the threads were leaking and air bubbles were coming out of there. Once I replaced that, there were no more air bubbles or leaks so I thought that had fixed the issue. But then when I started it back up after the replacement for the first time in a week, I am getting the water in fuel message on the dash and it's not going away. I don't think it's the WIF sensor because it's brand new. And I don't see why there would be any water in the filter since it's brand new as well. I am at a 1/2 tank, and before the replacement I didn't get the message either. I am not sure if it's some sort of glitch, or if there is actually water in the fuel tank. Any idea or experiences? Any suggestions are appreciated. Thank you
I had the same issue with my truck and I never did solve the issue. The wiring at the bottom of the WIF sensor are very vulnerable, so when mine looked suspect I got a new sensor and immediately go the light. Changed the sensor, same issue. Personally I think the aftermarket sensors are not compatible or are not made correctly to work with the WIF signal. It is a pretty simple on/off switch, if the float rises the switch closes and the light comes on. I checked all sorts of things including for of course water in the fuel and there was no issue. Only way to prove my point would be to be buy a OEM sensor and try it, which I have not done yet.
 

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Hi There. I just replaced the fuel filter, WIF sensor, and fuel filter head assembly on my 05 LLY. I replaced the filter head assembly because the threads were leaking and air bubbles were coming out of there. Once I replaced that, there were no more air bubbles or leaks so I thought that had fixed the issue. But then when I started it back up after the replacement for the first time in a week, I am getting the water in fuel message on the dash and it's not going away. I don't think it's the WIF sensor because it's brand new. And I don't see why there would be any water in the filter since it's brand new as well. I am at a 1/2 tank, and before the replacement I didn't get the message either. I am not sure if it's some sort of glitch, or if there is actually water in the fuel tank. Any idea or experiences? Any suggestions are appreciated. Thank you
Since you weren’t having the WIF light issue before you swapped out the sensor, why not just put your old GM sensor back in and see if the light goes out? If it does then you know that the new aftermarket sensor is bad and just replace with a new GM sensor. If the WIF light is still on then you have some other electrical issues.
 
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