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Go Back   TDIClub Forums > TDI Model Specific Discussions Areas > VW Passat Family (NMS and B7) TDIs (2012+)

VW Passat Family (NMS and B7) TDIs (2012+) Discussion area for the 2012+ Passat TDI (North American and rest of world versions versions). The North American model was previously codenamed NMS (New Midsize Sedan) and the version the rest of the world gets is sometimes referred to as B7.

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Old January 24th, 2020, 20:59   #1
otep858
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Default 2015 with no fuel pressure problem

I recently hit something in the road that ripped the wires off of the oil level sensor and i am trying to trace them back, however since that happened my fuel pump is not running, either by start button or by actuating the fuel pump within obd11. i can hear the relay click. but doesn't engage the pump either of them.. Does anyone know if the wires being disconnected from the oil level sensor will tell the ecm to not run the fuel pump? there is no other damage and the engine will crank just fine. not getting any more diesel at the filter. and yes there is plenty in the tank. also does anyone know the wire schematic for at the oil level sensor?
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Old January 25th, 2020, 04:10   #2
thundershorts
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Why not repair the wiring for the oil level sensor and see if the lift pump operates? The in tank lift pump does not by itself generate any codes, only shows low rail pressure codes. It would be logical to cut fuel in event of low oil level, such as sudden loss as would happen if pan were damaged or car were in accident.
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Old January 25th, 2020, 07:03   #3
otep858
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I will fix that as soon as I can find a wire diagram for it. I just didn't know if anyone knew for sure or not if that would tell the pcm to cut fuel

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Old January 27th, 2020, 01:34   #4
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Oil level sensor wires fixed. That wasn't what was causing the no signial to the fuel pump. Did find a bit of damage at the def tank and the wires that hook to the def pump. Have a new def pump coming. Hopefully that will be what is causing the problem

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Old January 27th, 2020, 07:11   #5
740GLE
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what the heck did you hit?

not sure if the lift tank wiring also follows the same routing of the DEF tank but with ODB11 or VCDS you should be able to verify the lift pump is working without def tank wiring or anything else.
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Old January 27th, 2020, 17:23   #6
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I could surmise how the faulty DEF wiring could prevent the engine from starting.

After all, if the ECU thinks the DEF tank is empty, the vehicle will not start.

So maybe that is what’s happening.

Good luck
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Old January 28th, 2020, 05:47   #7
otep858
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Originally Posted by 740GLE View Post
what the heck did you hit?

not sure if the lift tank wiring also follows the same routing of the DEF tank but with ODB11 or VCDS you should be able to verify the lift pump is working without def tank wiring or anything else.
I was following a truck on icy roads, and a down rigging piece of metal came off the truck and I was unable to serve enough to miss it. It trashed both tires and rims on the passenger side. Only wire damage I can see were the oil level sensor and the def tank pump as you can see in the pic. And it's more from the plug into the pump itself. 4 wires connect and only 2 leads are still connected... I used obdelleven to activate the fuel pump and it says something about can't resolve some issue. Does have a fault code (P208A) that won't clear in the reductant tank.

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Old January 29th, 2020, 06:40   #8
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If the tank is anything like golf, there is the cover which looks like the scratched part that can be removed to expose the wiring. I had similar occurrence with my golf and ended up replacing tank with a used one from car-part.com for 100 bucks.
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Old January 29th, 2020, 06:50   #9
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Good idea to replace the tank as in future you might get grief warranty wise as the damage is obvious. Its a item that junk yard doesn't consider a big seller so you ought to get one cheap, also not a hazmat item to ship.
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Old January 29th, 2020, 07:44   #10
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So the jolt of hitting that crap knocked damaged the connectors of the lift pump? That's just crazy bad luck.

IMO I'd be looking for just a new lift pump unless you see visual impact to the underside of the tank.
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Old January 30th, 2020, 05:47   #11
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Quote:
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So the jolt of hitting that crap knocked damaged the connectors of the lift pump? That's just crazy bad luck.

IMO I'd be looking for just a new lift pump unless you see visual impact to the underside of the tank.



No it didnt damage the lift pump at all. it hit the def pump. which is getting replaced, (part should be here today). And im thinking that the damage to the def pump is telling the lift pump to cut fuel off.
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Old January 30th, 2020, 06:14   #12
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I have seen cars that were in crashes have the fuel feed inside the tank on the lift pump break off.
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Old January 30th, 2020, 06:18   #13
740GLE
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My apologies, i thought you posted a picture of the lift pump connections, but that's the DEF pump.

Either way, I feel you should be able to force the lift pump to move fuel and build pressure with zero DEF system installed if you have ODB11 or VCDS.
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Old January 30th, 2020, 06:27   #14
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Quote:
Originally Posted by 740GLE View Post
My apologies, i thought you posted a picture of the lift pump connections, but that's the DEF pump.

Either way, I feel you should be able to force the lift pump to move fuel and build pressure with zero DEF system installed if you have ODB11 or VCDS.
I wish I could remember the exact error obd11 gave me when trying to activate the lift pump. But it was something along the lines of unable to resolve some issue. Def pump will be here today so hopefully we will know soon if that has any effect on the lift pump.

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Old January 30th, 2020, 07:19   #15
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Does def pump run constantly or only during regen? A whole deft tank assembly used probably would cost a fraction of cost of just pump and would eliminate some guess work,besides the cosmetics. Dropping the def tank is pretty easy and quick and can be done on jack stands.
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