The Dreaded N109 - Fuel Cutoff Valve...

Hi,

I suddently found myself quite low on power today. In fact, the car was running flawlessly; then appeared to be in limp-mode after sitting for just 10-minutes. I figured I had a boost leak or something. However, restarting the car did not "fix" anything... not even temporarily. I got to wonder all day what the problem could be. Since the car appeared to be in limp mode from the moment I started it, I assumed I had a bad sensor of some sort. I also had a quick "race" to 1800-rpm at each "cold" startups (car sits for 5-mins or more).

I scanned the car when I got home and found the following:

01237 - Fuel Shut-Off Valve (N109)
04-00 - Mechanical Malfunction

I performed a search at TDIClub and found good advice on how to remove N109. Unlike in other cases, the O-ring was right where it needed to be. The plunger came off and was still in the orifice. But it went right back into the main part. I spoke with Paramedick for a bit. Thanks for your help. Anyway, I connected voltage to see what it did. It appears to be working correctly. So I'm not sure what the deal is unless there is an internal resistance issue causing the ECU to "detect" a fault (much like detecting a glow plug harness fault). I reinstalled the part since I do not have a spare onhand.

My test drive found the fault was cleared; but the car was still in limp mode (no boost). A simple restart solved that. Power was back. I drove around for quite some time and the DTC did not return. Then I did a restart out of curiosity. The DTC returned and so did limp mode. I shut off the car, cleared the code, and restarted. The DTC was gone and normal driving was restored. Next restart found me in a fault/limp mode again.

Oddy enough, I did not find much about N109 in the "How to troubleshoot low power..." sticky in this folder. However, I think there should be a paragraph in there about N109. Here's why: I firmly believe my N109 glitch is putting the car into limp-mode, pulling back the fuel and boost. Unlike a boost fault in which power can be temporarily restored with a restart, this power loss remains in effect until the DTC is actually cleared. In short, an N109 DTC appears to cause a "low power" condition. Granted, I seem to have found a solution to this problem quickly enough. But I think it would be good to include it in the main write-up instead of folks hoping to find info via a search.

I took some photos and will include them in a removal/install write-up I will post later. For the record, a 15/16" wrench fits on N109 beautifully; but only after following Paramedick's recommendation to remove the wiring bracket. I will post my photos once I receive the new part. I'll also ensure all of my photo are clear.

If replacing N109 does not improve my situation, I'LL BE BACK.

Take Care,

Scott

PS: 203,000-miles and the car STILL hasn't left me stranded. Although I've replaced a few things, the car has been drivable with each issue... N109 being no exception. As my supervisor would say, "after 200,000-miles, that car doesn't owe you a thing." Yet it still comes through over and over again. I LOVE MY TDI!

Thanks for the bulletin, Scott. Looking forward to your follow-up with pretty pictures in it.

The fuel shut off valve is a simple solenoid, open or closed. It may be stuck in a partially (less than sufficiently) open position, but that would not cause "a quick "race" to 1800-rpm at each "cold" startups".
A partially open shut off valve would produce symptoms similar to a nearly clogged fuel filter, enough fuel for low demand operation such as idle, gradual acceleration, steady state driving at moderate speeds, but not enough fuel flow to keep up with hard acceleration, high speed, or maintaining speed up hills. You'd have boost, but only until the fuel demand exceeded the flow capability.
I suspect that you'll find the fuel shut off solenoid code is a result, not a cause.

Hi,

Lug_Nut said:

I suspect that you'll find the fuel shut off solenoid code is a result, not a cause.

Click to expand...

I still believe I was experiencing limp mode. My months with a poorly-designed T3 turbo package made me quite familiar with limp mode. It is still my belief the ECU entered limp mode after "perceiving" a problem with N109. BUT, with respect to your result vs. cause theory, what do you think about this:

Prior to installing the new N109, I opted to chase a squeaky alternator belt. If you've seen my other topic, then you know I have a faulty pulley. The pulley works well enough to prevent the idiot-dashlight from lighting. Do you think it's possible a tiny burp in the alternator output COULD cause the ECU to perceive an N109 issue? I tend to think not since the battery would fill-in the 12V needed to keep the fuel flowing. But it's a thought.

I will post my photos of the N109 removal later. I'm still chasing my alternator issues. I'm glad I took some time off.

Take Care,

Scott

Power spikes making the electronics freak out doesn't sound unreasonable...

-Jason

The N-109 shut off valve...

I have been experiencing the N-109 problem for about 10,000 miles. (The car only has 250,000 miles on it.) This comes almost a year after dealing with the N-75 problem as well as replacing all of the vacuum lines with high temp silicon. I also took the time to replace the KKK turbo with a Garret replacement and I took the time to clean my intake manifold. O, and I put on a 2.5 inch exhaust from the turbo back. After doing all of that the car an better than new! I mean it screamed on the highway!
Anyway, now this... I have been experiencing what all of the above posts explain except one thing... My ECU hasn't tripped a "Check Engine Light". Like I said before, the problem has been occuring for over 10,000 miles and still no light. I have'nt plugged Vag-Com into it yet (I know I should) but I am just finding it facinating that the ECU dosen't sense a problem, Yet there is no power on excelleration. I purchased a new N-109 and attempted to take off the old one a few hours ago. I did like the posts said and removed the small wire harness that blocks the valve from a wrench. I used a 15/16th inch open end wrench but could not get the thing to loosen up. I am worried about rounding the corners on it. Anyone have any tips? Thanks ~Matthew Hovis

Matthew, IIRC, I really had to smack the wrench with a rubber mallet to get it to break loose. However, I used the proper metric wrench. About $10 at my local hardwre store.

Hi,

I agree with using the proper 24mm tool. I was in a position where I needed something "NOW" and settled for a 15/16" tool instead. FWIW, I haven't continued to have problems with the N109. I suppose it's plausible the failing alternator pulley contributed to this perceived fault. Still, I have the spare N109 available and will use it when it's needed.

Since I didn't replace N109, I do not have the improved photos I hoped to capture. But are the ones I took when I first inspected N109:

Remove the torx bolts indicated by red arrows (obviously, the one on top of N109 is a nut)...


Here's a shot of N109 after removing the bracket holding the fuel pump harness...


N109...


Good Luck,

Scott

OK, I've looked and looked for a source of where to buy the N109 for my A3 (AHU) Jetta both in these forums and on the net.

So, at the risk of getting slammed here, where can I get one?

Craig.

worldimpex.com, 1stvwparts.com both good sources.

Neither places had an N109 listed on their website. Is it called anything else?

Thanks,
Craig.

Thetransporter said:

Neither places had an N109 listed on their website. Is it called anything else?

Thanks,
Craig.

Click to expand...

I believe this is the part in question:
http://worldimpex.com/item_detail.html?sku=177697

VW Part number and ETKA description:
028 130 135F - "fuel cutoff solenoid"

Perfect! Thanks a lot everyone!

Craig.

Hello,

I am having the 'surge at startup' issue and noted that in that thread it was hypothesized that the piston in the fuel shutoff valve needs a new "O" ring. Is this piston inside of the fuel shutoff valve? If so, is there a "how to" on the replacement some where or can some one just give me a basic "Ya take it out of the motor and it comes apart like this..."

Thanks,

Negative Ed

I just vag-comed over from RC2 to RC3 and got the same error code 01237, after I cleared it, it has gone away for now. Is this common? I took a look at the fuel solenoid and everything looked fine so I put it back in. I used a 6" crescent wrench (the max size happened to be exactly 24mm) this may be a good trick for the rest of you to avoid getting a 24mm wrench.

Just wanted to thank the OP for this thread. I have had my TDi for one week and I was able to solve my problem with this thread and a few others mentioning the N109 solenoid. I experienced the rev up at start all of a sudden and then noticed the total loss of power. I removed the solenoid and the o-ring was fine and intact, but I flipped it over and reseated everything. Now all is ok again. Thanks TDi club!

Beowulf said:

I believe this is the part in question:
http://worldimpex.com/item_detail.html?sku=177697

VW Part number and ETKA description:
028 130 135F - "fuel cutoff solenoid"

Click to expand...

FMTT, button up your shirt. . . your heart's falling out.

When you look-up the part listed on the Worldimpex site, they say the part only is good thru some 1999 cars.
What could be the difference from 1999 to the end of the ALH series? ANYONE?

I'm not having any luck finding a "fuel shut-off solenoid" for a 2000Jetta. But now I'm going to try "Fuel CUTOFF solenoid" and see what happens.

If you suspect the fuel solenoid is causing you problems, remove the plunger and put the coil back in with the o-ring.

This valve is superfluous on TDI's. Fuel cutoff is effected by the QA going to zero. The solenoid is a leftover from the mechanical pumps.

There's got to be a reason it's there. Otherwise, I'd think VW would have just put a plug there.

What's the need for the 12v, spring and plunger?

-Todd

I'd guess redundancy.

Not saying to leave it out but for troubleshooting it can do without it.

IDK, but I'm with Todd, I think there's a reason for it otherwise it would be gone along with the associated wiring etc.

I think part number is: 028130135F

Steve

It's there so you can turn off the car if the QA fails, the control collar sticks, etc. The QA is opening the spill port on the plunger which prevents the pump from building pressure. The shutoff solenoid cuts off the supply of fuel to the pump head completely.

Sent from my XT1097 using Tapatalk

You mean it's there for redundancy?

KLXD said:

You mean it's there for redundancy?

Click to expand...

No, it's the primary fuel on / off device for your engine, even if you believe that the QA going to zero will shut the engine off.

Deciding which actually acts first is like Schrodinger's cat in a way but I would be inclined to believe that the fuel shut off solenoid would be first.

Steve

Steve Addy said:

No, it's the primary fuel on / off device for your engine, even if you believe that the QA going to zero will shut the engine off.

Deciding which actually acts first is like Schrodinger's cat in a way but I would be inclined to believe that the fuel shut off solenoid would be first.

Steve

Click to expand...

You don't believe that QA going to zero will shut down the engine?

Say the injector pump plunger is about to start on an injection stroke, the pump cylinder already filled through the C/O solenoid.

I think shut down is going to happen quicker by QA opening the spill port before the the plunger completes its stroke and fires that cylinder, than if that cylinder fires while the the C/O plunger closes denying fuel for the next cylinder.

Even if the stroke is already started, when the spill port opens injection pressure drops to zero and the fire goes out. Before the pump even starts the intake stroke for the next cylinder

The QA was never intended to be the primary shutoff. QAs stick, they can fail, etc. The shutoff solenoid is usually super reliable and guarantees a positive shutoff. A contaminated pump for instance can have a sticky control collar or a blocked spill port, the shutoff will definitely work in those scenarios.

Sent from my XT1097 using Tapatalk

I'll say the solenoid was there first and so can be called the "primary". I'd still bet the QA beats it in timing but short of putting an o-scope on it I am speculating.

But you guys are begging the question.

My point was that the solenoid guts can be removed to see if the plunger might be causing a problem. The QA will still shut the engine down.

I suspect 028130135F is an expensive part to throw at it on a maybe.

I have had a jump wire hooked to mine for some time. Reason being, if i try to start the car it will not let the feul flow. So when i ran a positive to it, it clicked. But as i sat wondering if it would send feedback to the computer if something happened, my uncle popped up with the idea to put a fuse between, and a toggle for delivering power. So i still have it rigged that way. Not sure if our problems are related, but id love to find the root cause myself. Im thinking it has to do with burnt terminals in the ecm. Buying a new one to find out is ludacris when kermatdi sells a tuneable package. Im struck for other ideas and wonder if anyone else has tried to solder repair one.

N109 is fed through the little three-pin injection pump plug (the black and white wire), through the "orb of death" (the black circular plug on the head), back to pin53 on the ECU. It's pin 12 there, but it's kind of hard to figure out the wiring. Still black and white, and one of the thicker ones, IIRC.

It's probably simply a MOSFET on the board inside the ECU, and anything with the same footprint will have a better RDS(on) than what was available in '94-98 or whenever these ECUs were built.

But before you go tearing things apart, just take a test lamp and probe those locations with a test lamp. It's probably your orb of death earning its name. Obviously disconnect your jumper wire while testing or you'll just see voltage back feeding from it.