# 16826 EVAP leak, now how do I track it down?



## k_harley (Jun 11, 2005)

Car is a 1998 Jetta 2.0 auto
So Im getting the 16826 for a small evap leak. I checked the fuel cap and replaced it, with no luck. I also tried pressure in the line and it seems like it just comes out the filter next to the airbox.
Any suggestions on how I can track down the leak?
Thanks


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## penclnck (Jan 27, 2003)

*Re: 16826 EVAP leak, now how do I track it down? (k_harley)*

This can be a tricky thing to track down. I use a smoke tester, a device that pumps a "smoke" into the gas tank under pressure, thus a leak will blow smoke. 
Now you can check your EVAP canister and make sure it isn't cracked thus leaking. 
There is a valve in the engine bay that has a hose that runs to the throttle body. This valve controls the flow of gas fumes to the intake. If said valve is stuck open then you'd get the EVAP leak. Clamp off said hose and retest the EVAP system, if it passes, then replace the valve.


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## tjnamtiw (Nov 23, 2003)

*Re: 16826 EVAP leak, now how do I track it down? (penclnck)*

The valve in question is on the passenger side behind the airbox. It has an electric plug running to it. Take it off and run 12 volts to it and see if it clicks. If you don't hear anything, then it's stuck. Squirt some WD40 or alcohol in it and let it sit. Then hit it with voltage again while shaking it. Eventually it will probably come free. You just save a bunch of money and solved your problem. It worked for me! You actually have about 6.5 volts running to the valve, if you want to check the voltage at the plug, but 12 volts doesn't seem to hurt it for intermittent shots to see if it clicks. 
Good luck
Tom


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## k_harley (Jun 11, 2005)

*Re: 16826 EVAP leak, now how do I track it down? (tjnamtiw)*

VAG is saying that there is a small leak detected. That valve did click OK when I did output tests with vag-com. 
Ive been told that the smoke test is one way, just need to find a smoke machine. In the mean time, Ill try to bypass that valve and check for the leak, and clamp off other hoses and test them individually.
Thanks for all your help guys!


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## barmato (Jul 6, 2004)

*Re: 16826 EVAP leak, now how do I track it down? (k_harley)*

Not to worry you or anything, but I had the same problem with my R32. The problem first appeared when the car had about 2000 miles on it. I've been to the dealer 9 (yes that's NINE) times and they've done smoke tests, replaced lines, replaced the leak detection pump, replaced the gas cap, replaced the gaskets on the fuel sending units, etc. and they can't fix it. Now they refuse to try anymore because my car is modified. I hope you have better luck than me. I just clear the code every time it comes up (once every month or two now).


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## tjnamtiw (Nov 23, 2003)

*Re: 16826 EVAP leak, now how do I track it down? (barmato)*

This seems to be yet another of VW's infamous traits. Others are non-functional cruise control and the alarm system on the older (90's) VW's. No wonder they are rated at the bottom of the heap for quality. Sad day when that happens. http://****************.com/smile/emthdown.gif


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## Jagster936 (Feb 8, 2002)

*Re: 16826 EVAP leak, now how do I track it down? (tjnamtiw)*

I'm having the same problem! I have no idea where to find a smoke machine to use to try to find the leak. I'm thinking Im gonna try to trick it somehow...the code drives me nuts coming up every week or so :/
Anyone have any suggestions? thanks!


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## staytuned (Mar 26, 2005)

*Re: 16826 EVAP leak, now how do I track it down? (k_harley)*

go to basic settings 04 and fields ( if memory serves me correctly ) 70 71 and 77 and run a system check on the evap system and secondary air - you'll know for sure if your leak is in fact with in the evap system of vacuum lines of the system


_Modified by staytuned at 8:04 PM 11-1-2006_


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## Jagster936 (Feb 8, 2002)

*Re: 16826 EVAP leak, now how do I track it down? (staytuned)*

I'm talking about this on a different post, yes 71 is supposedly right I read it in the manual myself but it doesn't exist in my car. 70 doesn't either and I doubt 77 does because none of those high numbers around there does anything.
And how would it help in finding the leak?
And what is "secondary air"?


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## k_harley (Jun 11, 2005)

*Re: 16826 EVAP leak, now how do I track it down? (k_harley)*

So, it looks like I may have found the problem. I checked the valve at the bottom of the charcoal canister and it apeared to be non functioning. I think it was staying open when it was supposed to be closed. 
I put another one in there and am waiting to see if the code will come back. Hasnt yet, when it did before, Ill keep my fingers crossed!
Ive been trying to get the car into OBD readiness mode manually, but the evap system is the only one that wont go yet. 
Thanks for all your help!


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## Jagster936 (Feb 8, 2002)

How did you check it did you use output tests? 
I finally reluctently bought the ebaughn 3 day pass thing and it says go to address 33 then test 8 to run the test so I will try that today.
Do you think mine might be the same thing? This sure is frustrating. How did you find out valve wasn't functioning?
Thanks


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## Jagster936 (Feb 8, 2002)

*Re: (Jagster936)*

Pasted from ebaughn repair manual:
Function test 
Connect diagnostic tester => page VW-A3-FU02-ST-001-03ST-8. 
Start engine and let run 15 minutes at idle. 
Under address word 33, select "Diagnostic mode 8: Tank leak test". 
Measuring value "Test-ID 01: select Tank leak test". 
Check specified value of tank leak test at idle. 
Evaluation test-ID 01: Tank leak test 
Test function: 
Specified value: 

is being initiated, please wait 
aborted 
active 
off 
Test function active

Notes: 
During tank leak test, Engine Control Module (ECM) limits "test function active" to approx. 12 minutes. 
If the accelerator pedal is depressed during the test, the test will be aborted. 
To repeat the tank leak test, switch ignition off and start engine again and let run 15 minutes at idle. 
End diagnosis and switch ignition off. 
If a leak is detected: 
Check Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80- => page VW-A3-FU02-20-002-0820-47. 
Vehicles without Leak detection pump (LDP) 
Fuel tank ventilation, checking => page VW-A3-FU02-20-002-0620-40. 
Vehicles with Leak detection pump (LDP) 
EVAP canister system, checking for proper seal => page VW-A3-FU02-20-002-0720-44. 
Leak Detection Pump (LDP) -V144-, checking => page VW-A3-FU02-20-002-0920-50. 
Continuation for all vehicles 
Erase DTC memory of Engine Control Module (ECM) => page VW-A3-FU02-ST-002-06ST-26, Diagnostic mode 4: Reset/erase diagnostic data. 
Generate readiness code => page VW-A3-FU02-ST-003-03ST-51. 
Yea so I tried that 33 address word and it was found but it said "controller uses unknown protocol, keyword 0808"
More info for ROSS-TECH guys: "Init. Address 33 Try 1..
B: 10472 KW: 0808
So I guess vag-com won't initiate this test?
Hint wink nudge ROSS-TECH admins...should be fixed







. 
I guess manually running the test is out of the question then







. 



_Modified by Jagster936 at 10:47 PM 11-2-2006_


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## [email protected] (Jun 5, 2002)

*Re: (Jagster936)*


_Quote, originally posted by *Jagster936* »_Yea so I tried that 33 address word and it was found but it said "controller uses unknown protocol, keyword 0808"
More info for ROSS-TECH guys: "Init. Address 33 Try 1..
B: 10472 KW: 0808
So I guess vag-com won't initiate this test?
Hint wink nudge ROSS-TECH admins...should be fixed







. 
I guess manually running the test is out of the question then







. 
_Modified by Jagster936 at 10:47 PM 11-2-2006_

Address word 33 means Generic OBD-II:
http://www.ross-tech.com/vag-com/tour/obd-2.html


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## Jagster936 (Feb 8, 2002)

So how does this relate to that test they say to run then?
There is no "mode 8" gas link test..


_Modified by Jagster936 at 12:28 AM 11-3-2006_


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## Uwe (Jan 16, 2000)

*Re: (Jagster936)*

Mode 8 is not currently included in VAG-COM's generic OBD-II support. 
However, the EVAP purge valve is definitely included in the ECU's Output Test sequence, and you can run the EVAP system test on the ABA motor using Basic Settings group 153. Both are covered in eBahn if you know where to look:
VW Jetta 1998
- Repair Manuals
- - Fuel Injection & Ignition
- - - 2.0L 4-Cyl
- - - - 01 On Board Diagnostic
- - - - - VAG 1551 Scan Tool
There you will find a "Create Readiness" code procedure (the EVAP leak test is step 3) and the list of actuators covered under Output Test.
-Uwe=


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## Jagster936 (Feb 8, 2002)

*Re: (Uwe)*

Sweet, I see that basic setting I have been messing with it its real confusing but will post back with results...
Is it possible to reprogram the ECU and tell it the evap system doesn't exist? There has to be a way since all calls didn't have it necessarily. Can't you login the control module and disable it somehow?
I'm getting really tired of playing with this stupid leak and I want to completely disable the system if possible. I know when you put a new engine in you have to tell the system which features it has and stuff so you should be able to disable the evap..
Any input on this would be awesome.
Thanks!


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## Jagster936 (Feb 8, 2002)

*Re: (Jagster936)*

Yea that basic setting 153 works great. I also found the section on ebaugn you were talking about. Next step is finding the leak








Or figuring out how to disable the system altogether!


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## Uwe (Jan 16, 2000)

*Re: (Jagster936)*

If it has EVAP to begin with, disabling it would be illegal. 
-Uwe-


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## Jagster936 (Feb 8, 2002)

*Re: (Uwe)*

Yea probably so. It sure would be nice though







.


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## k_harley (Jun 11, 2005)

*Re: (Jagster936)*

Well, my code just came back after a week of thinking that it was fixed. UGHH...
Well, Im pretty sure I dont have leak in a hose, tank, etc. I pressure tested pretty much everything that I could. 
I get the code first thing in the morning, when its cold. 
Ive replaced the purge valve on the canister in the fender, that seemed to be junk. I also replaced the pump and the valve that goes with it. The only one I havent replaced is the releif valve. 
Is there any way I can moniter the position of the valve with vag-com?
We'll see how it goes.


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## k_harley (Jun 11, 2005)

*Re: (k_harley)*

So, I finally got to the bottom of the problem and corrected it. 
Turns out the signal to the canister purge valve had a bad ground so the valve just wasnt doing anything and staying open therefor creating a leak. 
I fixed it by making a new ground connection on the fender instead of using the one supplied in the harness. 
Its been a couple weeks and the code (or at least the customer) has not returned.


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