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2003 Volkswagen New Beetle GLS Convertible 1.8 Turbo
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Discussion Starter · #1 · (Edited)
I recently purchased a 2003 New Beetle for my daughter, and she is very excited about it. Now the fun part. It is a 1.8 Turbo, and it appears the person that owned it before me knew just enough to rig everything he touched. everything I look at needs attention, but the first goal is to get it through DE inspection. I've fixed the p0300(random misfire) by replacing the spark plugs. I've also fixed p0171(running lean) a vacuum leak after running a smoke test. those were the only two codes until recently when it decided to throw 4 different codes. Since I couldn't get my hands into the area to replace the crank shaft sensor, i took that to a mechanic $500+ later i'm 馃槶. Now it is only throwing p0420, which wasn't any of the 4 before the crank shaft position sensor. p0420 is "catalyst system efficiency below threshold bank 1". they want $1200+ to replace the cat, but I'm unsure i want to sink that much more into this considering the previous owners workmanship. if there are any quick fixes catalytic converter those would be appreciated. I would really love to know what the hose in the picture is. the previous owner had two pieces of hose wrapped with a small piece of hose, and it appeared to be superglued together.
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2003-2005 Volkswagen Beetle - Pressure Line - Volkswagen (1C0-145-712-E)


This boost hose just split in my 1.8T; seems it is only sold through the genuine VW and the URO brands, in rubber. Pricing seems similar between the two sources; i assume, the genuine vw part, is better quality then the aftermarket URO brand.


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2003 Volkswagen New Beetle GLS Convertible 1.8 Turbo
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Discussion Starter · #3 ·
Thank you!! Right now mine is rigged with two hoses and a coupler because I didn't trust the previous owner's superglued setup when i was having the smoke test done. It will soon be my daughters' car if I ever feel it won't break down on her. 200 miles this weekend, and no real issues, but catalytic converter appears to be the next $1200+ repair or it won't pass inspection..
 

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When, it comes to diagnosing the above code; there are some basic testing you can do and confirm the diagnosis. This video, shows the use of a scan tool to view live data and a infrared temp gun, to see if the catalytic converter is bad.


Lately, we have had some members; try catalytic converter 鈥渃leaners鈥 with positive results.

If you end up needing a new one; we have heard of positive feedback and results, using Bosal cats, a oem for VW. They tend ti be mid range price but oem quality and they pass emissions testing, cure related trouble codes, like the classic P0420 鈥渋nefficiency鈥 code..

Here is their online catalog; don鈥檛 freak out by the listed msrp pricing, they sell for much less online (rockauto, amazon, etc. or at local auto parts stores like AutoZone.






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If your 02 sensors are bad; stick with oem Bosch, here is their online catalog.


Also, be sure to purchase Bosch parts from a reputable supplier; as there are many, counterfeit parts being sold online @ Amazon, eBay, etc. A supplier, like FCPEuro.com; offers good prices, free shipping, quality oem parts and a lifetime warranty, on everything, they sell.


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2003 Volkswagen New Beetle GLS Convertible 1.8 Turbo
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Discussion Starter · #7 ·
it was suggested by my mechanic to replace the cat. since i'm now approaching the value of the car with purchase and repairs i've picked up the car to try other options.

First - I cleared the code(p0420), and drove it as hard as i could until it got through a drive cycle, and the code popped back up. the real reason for this was to also waste some gas so i could move onto a cleaner

Second - I put cataclean in it. directions say to drive for about 15 minutes(i think). I drove for about 30 miles, which I also drove it hard, with high rpms randomly. then I only filled it too 3/4 tank instead of filling it up.

Third - My plan is to try an o2 sensor extender. I've read people doing the spark plug nonfouler with great success, even on this forum, but the extender saves me trying to drill a hole without a vice.

Fourth - pay to have the cat replaced at a whopping $1250.
 

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I think the better approach; if the 鈥渃ataclean鈥 doesn鈥檛 work, is to diagnose the problem correctly, rather then throw expensive new parts at the problem and then, make needed repairs, replace defective parts. You can fix the trouble code or replace the catalytic converter WAY cheaper then $1250. Don鈥檛 get discouraged by a pro shop repair estimate; there is always a cheaper alternative solution, using quality oem parts and ending up with a correct, solid repair, passing your smog testing.

You could replace it yourself, saving $ on labor or buy the new Bosal brand down pipe/converter combo, for much less and/or have a muffler shop install it for you.

As to the 02 sensor 鈥渆xtender鈥,, idea; that may cause a fail for smog testing, visual inspection and the car would probably run better, have better gas milage, fixed correctly and have your fuel trims in spec, car tuned correctly.


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Discussion Starter · #10 ·
Boost hose was ordered, and hasn鈥檛 come in yet. The two pieces connected with a coupler should be fine until it shows up. After camshaft sensor replacement the only code that came back was p0420. I know fixing things properly is always ideal but I did try the o2 sensor extender because I didn鈥檛 want to exceed the value of the car in repairs. That eliminated the p0420 code in the first drive cycle. On fridays our dmv actually performs an actual emissions and not just plug into the obd, and it passed easily. I think the co2 reading was less then 12, so the cat can鈥檛 be too bad. While under there I checked to see if it was possible for me to replace it, and I don鈥檛 see that happening.

Next is addressing the tiptronic system. The dash will show PRNDS all blocked in after driving for awhile, and resets every time the car is turned off/on. Currently there is no noticeable drivability difference. Even before the letters are blocked in that tiptronic doesn鈥檛 function at all.
 

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As always, correct diagnosis; would require checking, testing the problem correctly, reading any trouble codes and this is really helped, using a VW factory level scan tool, like VCDS by Ross Tech:



I assume, you have the 09G six speed; we have seen, where the shifter assembly is defective and this can kill, the Tiptronic functionality. I worked on a 09G before and found, there were trouble codes, related to the shifter and the using VCDS, the computer didn't know, the right gear it was in, the live data, shifter position didn't match, manual Triptonic mode didn't work, shifting was not normal, odd shift points, hard shifts, etc.

After the shifter was taken apart; it became, very obvious, it was damaged and the selector sensor, was damaged and had to be replaced. After replacement, the testing showed; the gears matched, the trouble codes were cleared, kick down rest and the shifting quality was vastly improved, Triptonic feature, become functional.

There can be other faults, in the tranmission as well; we see, a wide range of problems, using VCDS, can help narrow down the fault and you can decide, how to move forward with any needed repairs.
 

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It sounds like you got lucky; on the smog testing and you passed, for this annual testing period. I would follow the testing shown in the ETCG1 video and that way, you can actually see, the efficiency of the cat and that would confirm the issue. A cat from Bosal, should be affordable and replacement, could be done at home or have a muffler shop, swap it out for you.

The extender, may not cause the fuel trims to be adjusted, as normal and the 02 sensors, maynot be able to read things accurately or as quickly, as they should, reducing fuel economy and engine performance. At a bare minimum, I would check your fuel trims and see where you are at, good 02 sensors, good fuel trims, definitely, make a difference in how the engine runs, your fuel economy.

So, now that you have "passed" your testing; you could, revisit this issue and try checking your codes, testing things, see if your cleaner, may have resolved things. There are other cleaners on the market; that could be something, to try as well and some of these, actually have specific procedures, driving cycle, that gets the cat as hot as possible, allowing the cleaner to do it job, rather then, just a cleaner, then driving, how you would normally drive. We have had a number of members; who, have tried these and it has fixed their cats and cured the efficiency code.


Tuning up, you 1.8T: would definitely, be something to consider and you can be amazed, on how well the 1.8T can run, when tuned up and running correctly. In the last couple of years; I have been working through, a series of issues and diagnosis, testing, retesting and process of elimination, to get mine running, the best it can. These are great engines but after 100k, 15-20+ years; many parts, are worn and the engine performance suffers, as the degradation is gradual over time or you got the car in a poor running state to being with, it can be hard to know, how it should run, running WELL!
 
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