By on July 6, 2016


iphone dongle. shutterstock user Zeynep Demir

Dan writes:

Dear Sajeev,

I’m looking for some advice on a reliable, yet affordable OBD-II scanner to look up and clear the check engine light (CEL) on my 2010 Volkswagen Golf TDI. While a dedicated Ross-Tech VCDS would be ideal, the price and future ownership of this (or any other VAG) vehicle is not.

Emissions issue aside, the Golf has been reliable except for having to replace several tires (and one wheel) over the years due to pothole-riddled roads. Besides regular maintenance, I’ve replaced a glow plug ($120) and the CEL has recently returned yet again. I suspect another glow plug is to blame.

Onto my question: What do you think of one of these wireless/Bluetooth dongles that work with a smartphone app? I’m leaning towards one of these as they seem to offer more options than the traditional cabled versions. Can you or the readership recommend a good iOS/Android app?

Sajeev answers:

The VAG-COM is not a system for casual wrenchers with a “normal” OBD-II scanning budget. Even older VWs have trouble with cheap ($50-ish) and really cheap (under $20) code scanners. If there’s a decent 2010 VW code scanner or dongle and software package for under $150-ish, my Google-fu ain’t savvy enough to find it.

Ross-tech is your best bet, but not the free software for older models. I wouldn’t even trust a generic dongle unless you’re computer savvy enough to find the right (laptop) drivers. Perhaps consider the Ross-tech cables too. Unless you read otherwise about a fantastically magical generic VAG-COM dongle and/or software on the TDI forum, of course!

Or just have the person at Autozone scan it for you. You can probably convince ’em to clear the codes if you come back later and say, “I fixed it, can you clear it for me?” Whether or not you actually fixed the problem is a whole ‘nother story.

Or don’t listen to me, because following up with Dan yielded this: 

I did go with a wireless OBD-II scanner. I tried a few of the free apps and settled on OBDCarDoctor (iOS). The CEL turned out to be a faulty exhaust valve flap covered under extended warranty.

While I will take the deal from VW to sell back the car, I’m in no rush to do so. It’ll be bittersweet to let this car go.

[Image: Shutterstock user Zeynep Demir ]

Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice. 

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48 Comments on “Piston Slap: The Affordable VAG-COM Dongle Tool?...”

  • avatar

    A VAG-COM is practically the price of admission if you ever want to work on your own modern Volkswagen. The first time you can clear a code without going to the dealer, or fix some minor thing, again without going to the dealer, it will pay for itself.

    • 0 avatar

      Clearing a code doesn’t fix the problem.

      • 0 avatar

        You obviously don’t own an 11 year old Audi, JimZ,

        Half the problem with old VAGs are the various, random codes and warnings. Some mornings, your dashboard has more lights than you knew existed, and all the beeping is difficult to tolerate. “Drive to nearest workshop immediately.”

        I would be happy if all the warnings would just go away, leaving me to drive in ignorant peace until it finally does die. Hopefully quietly.

      • 0 avatar

        As VoGo mentioned, sometimes VAG products throw random codes. Plus, a VAG-COM can do so much more. For example, replacing the rear brakes on my wife’s old Passat wagon with the electric parking brake required the VAG-COM to reset the calipers. Just doing that job at home saved me more than what I spent on the dongle from Ross-tech. Another example is chasing a misfire, or the TDI near equivalent, the bad glow plug. Easy to do with the VAG-COM and you save on the labor.

  • avatar

    Carista bluetooth works fine on 2008 Audi S5. $40 for the unit and $20 for the software that allows changes.

  • avatar
    Chris Tonn

    The ever-present 12 year old boy inside of me is giggling at the presence of “VAG” and “dongle” in the title.

    Otherwise, I love my BAFX Bluetooth OBDII reader, paired with the Torque app on my Android. Cheap, and seemingly accurate.

  • avatar

    So I wonder what code it will show when VW drills a 4 inch hole through the engine block after you sell the car back to them.

  • avatar

    I used a really cheap eBay dongle and the free Ross tech software to read the transmission temperature while doing the fluid change in my ’09 Jetta. Worked well enough to get the job done. Ross tech’s site is confusing when it comes to the correct drivers, but I got it to work on my old XP laptop.

    • 0 avatar

      My first VAG-COM set up was the purchased software and an eBay cable. That worked fine until my laptop with the COM port died and its replacement didn’t have COM ports. I bit the bullet and purchased a dongle USB cable from Ross-tech, which works just as well.

  • avatar

    Proprietary diagnostic equipment: a requirement for 5+ year old VW ownership :p

    Half kidding, I can appreciate having that sort of capability as a DIY guy.

    • 0 avatar

      I recall many an evening sweating in the garage with my HP laptop and Ross cable hooked to the A8.

      P0442 FTW.
      P0456 FML.

      And what was the P0456? A hose or something causing the small EVAP leak? Nah, it was the warped plastic disk on top of the fuel sending unit – a part which in 2009 was no longer produced for a 2000 model.

      And what do you gotta do to access that fuel sending unit? Take a part the entire damn trunk.

      Then replace it was a retrofit fuel sending kit, of which they needed one part (the plastic disk).

      I’m still mad at Audi.

  • avatar

    My brother runs a repair shop and he doesn’t believe in code readers for us mere mortals. He says, you will get a code that says oxygen sensor but it’s really the wire to the sensor that is bad. His real problem is people come in thinking they are saving the diagnosis fee by telling them to replace the part and then when that does not work they get all upset.

    • 0 avatar

      I have to agree with your brother. If you’re not going to fix the car yourself, trying to diagnose the problem in the hopes of saving some money is problematic.

      • 0 avatar

        We should also remember that there are a lot of mechanics who are not always 100% honest. My wife brings our Audi to the shop – even a well reputed specialist we like – and I know they will do an oil change, even if they’ve done one a month prior.

        Being an educated consumer – especially if you are a woman – can be worth the price of entry on a VAG-COM.

    • 0 avatar

      I like to put it this way- if your shoulder hurts, you go to a doctor and say “my shoulder hurts.” He/she then has to do some diagnosis to figure out *why* it hurts (arthritis, torn rotator cuff, etc.) So your car throwing a DTC is basically saying “it hurts here. please figure out why.”

  • avatar

    I had the same problem as this guy with my TDI. I took the car to a non-VW place who read the code for me. If a decision is made to keep the car beyond the warranty, there are some amusing YouTube videos showing how the flap can be fixed without replacing the part. VW actually helped out with the repair (which was outrageously expensive particularly given what is shown in the videos) since I wasn’t quite up to the skill level required.

    VW actually extended the warranty to 100,000 miles on some models for a similar problem, but apparently there are both intake and exhaust flaps and sometimes they covered one and not the other. Sigh.

    • 0 avatar

      What the hell is an “exhaust valve flap”? Has to be some damn diesel exclusive piece. Why do you guys buy those cars?

      • 0 avatar

        The TDI I owned was my favorite car. It straightened curves and flattened mountains. It had heated leather seats and a sunroof. It was beautiful, interesting under the hood, and fun to drive.

        At least on those occasions when it ran. Great driving experience. Really terrible ownership experience. Worst car I’ve ever owned, on balance, and I’ve owned some real rust buckets.

        • 0 avatar

          This was EXACTLY my experience. Golf handling, the sport suspension settings we don’t get in the US, huge soundproofing, great seats. Bulletproof highway cruiser….BUT, and a huge BUT, Largest repair bills for any new car I’ve ever owned under 100,000 miles, by a very large margin.

      • 0 avatar

        The exhaust valve is to regulate back pressure in the system for regeneration cycles. The problem is that the return spring is outside the assembly, so if, oh, you live in a world where your car sees salt, the spring will eventually jam up. Now, I don’t know how cars get salt on them, or how VW could have known this, but yes,under the car, in plain sight, is a spring. The warranty for the new part is 120k miles. Mine failed just in warranty, unlike my diesel particulate filter, which died just outside warranty, and was NOT covered.

  • avatar

    I have the VAG COM program and the dongle. It is worth the money. If you want to save a few bucks Google ‘CARLY FOR VW”. I have their set up for my Android phone to work on my Mini and it works great. Program was under $50,00 and the OBD II plug was like $28.00. Works great for turning off service lights, coding, Recoding a new battery (A BMW thing) and many other things. This is a German company that knows what they are doing. You can also find them on Amazon.

  • avatar

    There is a new kid on the block called OBDEleven, an Android-based program & wireless dongle, for reasonably cheap cost, that apparently works quite well. No personal experience. VCDS/VAG-COM has been around forever and the support for it is excellent, and it’s a VERY comprehensive tool.

    • 0 avatar

      I have this for my B4 tdi. It’s Lithuanian and the interface is kind of crappy. It works for reading codes and measuring blocks but in my car (a ’97) adaptation refuses to work.

  • avatar

    Does anyone know of an OBD-II dongle that works with the Ford C-Max Hybrid? I have a Garmin Ecoroute dongle that I can’t even get power on from the C-Max OBD-II port.

  • avatar

    I have an ELM 327 dongle from Amazon and use the Torque app typically. It will at least give the relevant Pxxxx code to help you out. I’ve also used Carista a bit but Torque (free) seems better.

    The ELM 327 and the Torque app helped me diagnose that my exhaust flap was failing before I called the dealer to get the replacement setup.

    • 0 avatar

      Elm + Torque = dirt cheap and SUPER reliable. I’ve had mine for years and have used it extensively for family, friends and co-workers. I also use it to datalog my Mitsu.

      It will work just fine clearing cels on your junk VW.

      • 0 avatar

        Yes and yes. I think I paid $11 on Amazon for Elm 327 – I love the small profile but not the weird blue light it emits. I bought the Torque app for a one time $5 charge. My tablet sits on the dash, and I almost crashed the first time i used it. I also was flabbergasted by the puny amounts of HP i use driving around in a car with a 255 potential hp.

        • 0 avatar
          bumpy ii

          Common misconception. People read that their car “has 300 hp” and think it’s making that all the time. Nope, only when you have the go pedal mashed down and the tach is just short of hitting the rev limiter. Cruising around on the highway, it’s only making whatever 30-50hp is needed to push the air out of the way and overcome the rolling friction of the tires.

  • avatar

    Former mechanic from the last century states;

    Kicking and screaming, I was placed into the 21st century, learned Chevette ALDL plug terminal wiring, SnapOn brick jockiing CCC systems & joys of VAG. The good old days of D,L,K Bosch EFI before the “E” suffix made the older systems instantly obsolete. Learning the value of a good, accurate fuel pressure gauge.

    But technicians are not engineers, nor manufacturers of the next stupid engineered system that is currently broken in their bay. Taking book knowledge & practical fixed broke car knowledge, the car got fixed. No halfass shortcuts, the way it was designed.

    Only related the story to make this analogous point; You cannot work on, or operate, or even service, an S3A US Navy jet aircraft, WITHOUT the TOOLS and NATOPS manual and EXPERIENCE to understand the problem & how to perform the job. Always remembering that a LITTLE knowledge is WORSE than too much

    Serious German car o phials will have the specific VAG tool AND TOOLS to do the job. Then, they WILL be prepared to get/have the knowledge to know WTF they are looking at / doing. Think brakes are NOT working. It’s too late to do the “right” thing. You really do not want the “pound of cure” category Alex.


  • avatar

    The TDICLUB website might be a good source of information on that.

  • avatar

    The VW dealer wants ~$100 just to hook your car up to their scanner. Even then they apparently can’t do what VCDS can do. I bought a VCDS compatible dongle years ago to diagnose a TPMS fault. I was pretty sure it was a problem I saw described in a VW forum. A software bug can cause the TPMS monitor to set the low tire pressure threshold way above the correct value. I described what I knew to a VW mechanic, but he had no idea what I was talking about or how to correct it. I asked him if he, or anyone there, was aware of the online forums or VCDS. He literally told me, “…most of us (VW mechanics?) don’t drive VW’s,” and went on to suggest replacing the TPMS receiver buried somewhere under the dash.

    The VCDS cable and software allowed me to verify and clear the problem myself. Later I used it to diagnose a faulty exhaust flapper. You can also use it to convert the TPMS system in some older VWs that use wheel-sensors into the sensor-less speed-sensing system employed on new cars, or vice-versa. You can re-calibrate the speedometer for different wheel diameters. There are also many tweaks you can make to the car’s computer controlled systems that I’ve never played with.

    I won’t own another VW without one.

  • avatar

    2010 TDI? I wouldn’t spend much on a tool if VW was buying the car back soon.

  • avatar

    Here you go. Find someone near you and offer to buy them a sixer of their favorite beer. Maybe make a wrenching buddy too.

  • avatar

    Personally, all I want is a simple, cheap, digital tachometer that doesn’t require a hard-wired connection to the engine of my ’97 Ranger. The one I own did not come with a built-in tach.

  • avatar

    VAG cars seem to have a habit of setting totally random intermittent fault codes. Rather than just replacing parts based on a fault code, having the ability to leave the reader plugged in while you are driving is often helpful in figuring out what is “really” happening.

    My Audis never stranded me in the 15 years I owned them, but I did have a few warning light issues. I owned the full USB version of

    My Audi TT used to trip the Airbag light on first thing every morning for about 5 minutes. I was able to remove the steering wheel position sensor drill out the plastic visits, clean , reassemble and calibrate it with A new part would have been $700 online, the dealer wanted $1500 to install.

    The full allows a higher level of recoding, on my early 1996 A4 you couldn’t clear the service reminder lights without the full version.

  • avatar

    Ross Tech has gotten my money twice. I started out with a cheap $20 dongle off eBay and VAG-COM shareware as a trial to see if I ought to invest in the real deal. After a month, I was blown away by how much VAG-COM could do, so I bought a serial dongle and license from Ross Tech for ~$150. 10 years goes by and my laptop finally goes kaput. I gave Ross Tech a call and bought their USB dongle with license for $200. I wouldn’t own a VW/Audi without VCDS (VAG-COM).

    As for my wife’s 07 Lexus Rx400h, I bought a clone copy of Techstream on with a dongle for her car and it’s been a godsend. It’s exclusively required to perform simple tasks such as brake fluid flushing (due to the electronic brake actuator) and more complex tasks such as recoding duplicate keys.

    At any rate, both VAG-COM and a cloned copy of Techstream are well worth it.

  • avatar

    If all you need to do is read codes and clear them and make a few basic modifications, Carista plus a Bluetooth dongle is a well-spent $45.

  • avatar

    Xtool VAG401 – $58 on Amazon. Can’t do everything that VCDS can do, but does most of the essential stuff.

  • avatar

    Autel VAG505 around $150 Is a scanner plus is will do stuff like reset the Audi 10,000 mile service reminder and the EPB rear parking brake retraction so that you can change the rear brake pads.

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