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Discussion Starter · #1 · (Edited)
So my daughter tells me the SES/CEL/MIL came on in her 2003 1.8t Convertible. She is pretty observant and has been trained to not just drive around with lights on the dash lit and keep this information to herself. +1 for the daughter promptly informing dad there is a problem! Not sure if the dad or daughter should take credit for this.

So I ask is there anything different about how the car is running and she says she has not noticed anything specifically different. The car is a convertible and the weather has been good and the top was down, so I take the car for a quick test drive. I am probably a bit more aggressive with about my driving then she is, but again, I have been driving for over twice as long as she has been on earth. I also grew up driving late 60's, early 70's American Muscle cars, so I have no reservations using the right pedal.

Did not take me long to hear/realize there was some loss of boost and/or a boost leak based on the sounds coming from under the hood. If the top was not down and the windows would have been up, it may have been less obvious or I may have missed the "boost leak" noise.

So back in the driveway to get some information. I have VCDS Lite somewhere on an older laptop and was too lazy to find it. I have PLENTY of OBDII tools, everything from smart phone Apps to Pro level tools like SnapOn Modis and Solus Ultra and a few other in between tools. Also wanted to try my $40 VAG405 as well. Kind of wanted to see how all the different tools would read and display errors.

I start simple and see what I am dealing with.

P0172/P1166 (VW specific), vehicle too Rich condition and P0441 Evap Incorrect Flow. Wow, this does not happen often. Check LTFT, heck they are in the upper -20% range. This is NOT good. I think to myself, how can a car run so Rich or being told it was running so Rich. So before I clear any codes, I decide to get some of my more advanced tools out and read further. Funny thing is the car starts, idles and generally seems to run fine otherwise.

I initially think maybe the Evap solenoid is leaking and causing the Rich condition, but I also have a P0441 Evap code. Scratch head a bit and try to think about what info I have at hand.

I have an electronic Bentley and I did not spend much time looking at that. Unfortunately I have not studied or tried to find a comprehensive theory and operation of the 1.8t induction and turbo system. It may be available or out on the web, but I have not found anything "good" with a diagram and description of operation.

Anyway, start searching the forums, and thinking things over in my head. Also reset the codes to see what codes come back and if there was an additional info I could gather while researching the problem. What I found interesting is almost all the forum posts point the finger at the Diverter Valve and/or the N249 or N75 valves. I think about this for a while and I decide it is not likely a valve or control solenoid. I also have a Evap flow problem that could be a questionable solenoid or it could be related to what I have heard as a "boost leak".

Since most SES/CEL/MIL problems are not catastrophic and the report that the car was not running unusual, I figured I would throw the hook back in the water and keep fishing for more data in the meantime. I get a report that the SES/CEL/MIL is back on, which I expected, so I start to read for codes and this time with my Launch CRP123 I pick up 2 VW specific codes.

17574 - LTFT Bank #1 too Rich
17705 - Pressure drop between Turbo and Throttle Valve (check D.V.)

I do not think I used my other tools at this point, just happened to try my Launch CRP123.

So I think, again, something pointing at the Diverter Valve, which many have claimed are problems on these engines. But I am just thinking, the noise of a boost/air leak has me puzzled along with the fact the engine starts, idles and runs pretty much as normal. Also the idle MAF reading in Grams/Sec is normal, so I am thinking I do not have any specific air leaks in the intake system, again, this has be a bit puzzled or curious as to what is really going on.

So being the kind of person I am, I decide, time to go old school. Act like I have no OBDII or advanced scan tools. I have some clues and know where I should focus so this saves me some time. So I start by a good visual inspection looking for obvious things that may be out of place, disconnected or have some sign of deterioration. Nothing stands out. Next on to the "poke, pull, squeeze and feel" testing.

Well it does not take me long until I find that the hose between the diverter valve and the rear boost pipe has what appears to be a soft or bad spot in it. This hose has a partial rubber protective sleeve on it as well and the soft/weak spot was on the underside of this hose, under the protective sleeve. After more closely squeezing and manual inspection with my fingers I find a small crack/slit on the underside of this hose even all the way through the protective rubber sleeve. I think to myself, BINGO, Houston we have a problem!

So then I realize, this hose is on top of the rear of the engine and is right above the turbo/exhaust and a insulated boost pipe. This area is subjected to a lot of heat and the rubber has broken down after 13 years. Short term solution is to repair the hose with duct tape while I search for a replacement hose. Duct tape sealed this hose up and the boost leak was eliminated for the short term. Called my local dealer and they did not stock the part and wanted like almost $80 for the hose. Decided to poke around online and find a better price. After some searching I found the same hose for around $33 and even with shipping it was almost 1/2 the price of what the local dealer wanted.

Then after some more thought I realized that what actually was the best test tool for this problem ended up being my visual and ""poke, pull, squeeze and feel" test. Granted the OBDII/Scan tools helped me narrow down what was going on, but also using my head, experience and also calling BS on all the N249/N75 and diverter valves that are constantly replaced, I decided to pass on all of these more "common" repairs for this problem. Then once I found the problem and thinking about it for a bit, I realized this hose, along with others, should have been replaced around year 10. I also realized this hose probably did not fail catastrophically and likely has been leaking for some time under the rubber sleeve and the boost leak probably was not as loud or noticeable. So a word to the wise, suggest anyone with a 1.8t anything, the boost bypass hoses should all be replaced by now.

I can see specifically this hose between the diverter valve and the boost pipe is likely leaking on MANY cars and people do not realize it is leaking and possibly compromising performance. This hose can easily fall below the radar with the protective sleeve covering part of the hose and acting like a check valve, only letting air out under high boost pressures.

As for the Evap P0441 incorrect flow problem, I will wait it out a bit to see if in fact this code was actually triggered due to the boost bypass hose leaking. I may have a faulty purge valve or some other problem, but I will take a wait and see approach.

Yes, this is a long story, but I thought I would share my experience and what I found on my car. Using the basic old school troubleshooting techniques can still be relevant even with today's cars. Eyes, ears, fingers and the brain along with the "poke, pull, squeeze and feel" testing is still more accurate that the most advanced software or stand alone tools.

Yes, VCDS, VAG405 or other Pro or even smart phone/tablet OBDII Apps can be helpful, but rarely will ANY of these tools point to the exact problem and they often mislead you into think a sensor or electrical part may have failed when in fact there are often more basic problems. Use the KISS principle, Keep It Simple Stupid. Most of the problems are usually hoses, seals and gaskets on the older cars. Yes sensors, solenoids fail, but plastic and rubber under the hood of a modern vehicles does not last more than 10 years reliably.

Hope this is helpful to others that may run across this thread.

Picture of hose attached to engine (located between colored arrows), not my car and does not have rubber protective sleeve, but for reference purpose so folks can understand where this hose is located and what it generally looks like.

Additional pictures of hose failure once removed from car and old and new hose up against each other. Hose failure tends to be on the bottom/underside of hose due to the heat and is not visible until hose is removed.

On turbo pipe side the one time hose clamp needs to be replaced with a medium worm drive hose clamp.
 

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That's a great tip, jfoj. I should change out those hoses too. Do you or anyone else know the OEM part number for those set of hoses near the back of the engine? I remember seeing it being sold as a complete assembly, but now can't seem to find it anywhere.
 

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Discussion Starter · #4 ·
The hoses differ per model, so you will need to look them up for your vehicle.

I am not a big fan of jumping on the silicon hose bandwagon for most applications due to the cost. My original hose lasted 12 years, so I think an OEM hose for $33 is probably the way for me to move forward, it likely will last another 12+ years as the part number has been updated as well.

I did not check on the silicon hose pricing, but I know on some applications they can sometimes be close to 10 times the cost of a rubber hose. Maybe in this application it is only 5 times more expensive, I have no idea.

I really doubt I will still have this car on its 24th birthday, but if I do, I will be replacing these hoses again and a LOT of other parts!
 

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Discussion Starter · #5 ·
Update on hose part number and pricing.

For my AWV 1.8t 2003 GLX motor the hose part number is 1C0-145-712-E. My local dealer did not stock the hose and wanted like $82 for it. I asked if they would price match Online pricing and they said they would look at doing it. I just tossed a $45 number out as I had not fully researched the pricing. My local dealer told me it was under their cost.

So I ordered this hose along with a different hose from VW Parts 1st. The hose I needed listed at 58.52, Online price of $35.11, along with my other hose, I paid $8.95 shipping.

So still FAR cheaper than getting it from my local dealer.

I would suggest anyone with a turbo motor, change this hose between the diverter valve at/by year 10. If you have not replaced it yet, start getting parts and plan on some PM time before the hose blows on you in the middle of the Winter.

It is an easy 15 minute swap as long as you have the replacement worm drive hose clamp on hand.
 

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Thanks to jfoj for this fix

This is an old thread but I'm bring it back up because it finally let me find the cause of the too rich/too lean/P1297 (pressure drop between turbo and the throttle body) codes on my daughter's 02 GTS Beetle 1.8L Turbo

THANK YOU - the back side of the hose was worn thru just as you pictured. I just janky-repaired with some old RX7 90 degree bends and some 3/4 heater hoses for now. The correct hose in on order via Amazon.

Seems to run better and I don't hear the boost leak anymore... Let's hope the check engine codes stay away...

I have been racking my brain trying to figure out what would make an engine run both rich and lean - and a boost leak now makes sense - it was lean under vacuum (too much air) and rich under boost (not enough air). It actually didn't run that bad... considering there was a 1 inch long tear in the hose.

AGAIN - THANK YOU !!!

BTW - the hose is about $37 on Amazon these days - with shipping.
 
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