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FAQ - OBDII Diagnostic Device Reviews

13K views 2 replies 1 participant last post by  SwissJetPilot 
#1 · (Edited by Moderator)
For the purpose of this discussion the term "OBDII Diagnostic Device" includes any diagnostic device that can be used to interrogate and report on the status of the electronic system of the Mk1, Mk2 or Mk3 TT by means of the OBD port. For the specific details on the differences between VCDS and OBDII, see the notes below. For anyone unfamiliar with the technology, this link to Wikipedia provides some history and basic understanding of OBD diagnostic and how OBDII devices came into being.

As the market for OBDII scanners continues to grow in both popularity, options and price point, the Forum is collecting more information from our members on how to use these devices and their personal opinions on how well they work. Each manufacturer has their own functional capabilities and feature which generally include -

• Fault Scan
• Fault Clearing
• Service Reset
• Output Tests
• Adaptations & Basic Settings
• Code changes to enable or disable factory set functions

Four Reasons to Own One -

1.)
The ability to find out for yourself what's going on with your car when you suspect there's a problem. Rather than guessing or depending on a service garage, you can quickly check it yourself, look up the fault codes and then decide if you want to tackle the repair yourself or take it into a service center. By knowing the fault codes ahead of time, you can have an educated discussion with the shop so you're less likely to get pulled over the table. For the DIY mechanic, think of an OBDII scanner like owning a torque wrench - you should just have one to do the job right.

2.) Access features not present in your TT when it left the factory and performing Adaptations and Basic Settings. For example swapping the OEM DRLs with LEDs is possible but you'll need re-code it in order to make this work. Other possibilities include Service Reset, Oil Service Reset, Reverse Camera installation, Needle Sweep, etc. Keep in mind not all years will have the same options or features.

Adaptations, Basic Setting and Initializations are slightly different in how they are performed but are necessary when replacing sensors and some electronic components. An Adaptation and Initializations usually involves entering a value, such as idle speed, where you have different choices. A Basic Settings is a single pre-determined routine where you have no choices to make such as when you replace a G85 Steering Angle Sender. If the Workshop Manual states a calibration is required after replacing a component, it will not be possible to clear the fault code until either an Adaptation, Initialization or Basic Setting has been done. You can read more about Adaptations here.

3.) For anyone looking to buy a TT, it's always a good idea to ask the seller if they are willing to provide you with a fault scan as part of the pre-sale. If they refuse, you may want to walk away from the car or just take it for a test drive and run the test yourself. With any pre-sale, you should have a mechanic go over it so there are no surprises and include a fault scan as part of the inspection.

4.) Running a full back up. A full backup will read all of the available channels, coding values and Adaptations and store them into backup. It's a good idea to create a backup of every control unit before making any code changes. If you have to replace a control module, you can upload your saved data so the new controller will function like the controller you are replacing.

Just be aware not all scanners are the same. They can't all perform all Adaptations & Basic Setting, output tests or export data files and not are all coded specifically for VAG software. In a nut-shell, you get what you pay for with an OBDII scanner.

OBDII Reviews -

Below you will find a brief list of pros and cons for each OBDII scan tool along with a link to the Forum review and the product's home page. These are sorted by capability and price.

VCDS vs OBDeleven -

This video from Charles the Humble Mechanic goes over the various cost and feature options of both VCDS and OBDeleven. At first glance, the VCDS HEX-V2 seems more expensive than the OBDeleven Pro. However the OBDeleven Pro also has an annual subscription fee. So over the long term it could end up costing you more.

Roadster Owners -

If and when the roof fails to work properly, you can run a fault scan with either an OBDeleven or VCDS to find out which DTC is being reported. However, at the time of this writing, the VCDS is the only diagnostic tool that can provide the required Adaptation/Initialization and clear the fault.

First Time Users -

Once you get your OBDII device, if this is the first time you have used it be sure to run a full auto scan with the engine running. If any faults are reported, clear all of them. Then go for a drive for about 10-minutes including (if possible) some highway speeds. When you get back, run another scan and those faults are the ones you want to pay attention to.

From there, look for commonly related problems; e.g. is the manifold reported multiple times? Is "low voltage" reported frequently? Low voltage (< 10.4 volts) can cause all kinds of problem to multiple systems. See the information at the bottom of this page on how to search for fault codes.

Parts or components should not be replaced with reference to only a DTC. The vehicle service manual should be consulted for more information on possible causes of the fault, along with required testing.

For example, if a DTC reports a sensor fault, replacement of the sensor is unlikely to resolve the underlying problem. The fault is most likely to be caused by the systems that the sensor is monitoring, but might even be caused by the wiring to the sensor itself.

DTCs may also be triggered by faults earlier down the line. For example, a dirty MAF sensor might be causing the car to overcompensate in its fuel-trim adjustments. As a result, oxygen sensors are likely to report fuel mixture problems.

OBDII User Poll -

We also have a new poll going on just to get an idea of which of these is the most popular with Forum members. In all fairness, VCDS has been around for over 20-years, while the OBDeleven has only been on the market since 2015, but it's gaining popularity. To visit the poll, click here

1. Ross Tech VCDS (VAGCOM) -

VCDS-01.JPG

FAQ - VCDS Open Box Review
https://www.ttforum.co.uk/forum/viewtop ... &t=1928927
Ross-Tech: Home
Ross Tech YouTube "How To" Channel www.youtube.com/user/RossTechVCDS/videos

Pros:
• PC based (Windows)
• Stand alone, does not require internet access to work
• Has all Adaptations and Basic Setting functions
• Multiple Measurement Block viewing
• Live Graphing of multiple systems
• Data export feature
• Video Tutorials, Forum and Wiki pages
• Direct customer support
• Free software upgrades
Supports VAG software
• No additional costs

Cons:
• Price
• Hex connector and cable are usually used with a laptop.
• The least expensive HEX-V2 is limited to only 3-vehicles.
• No programming short cuts; long code only.

2. OBDeleven (FirstGen & NextGen)

Gadget Rectangle Font Musical instrument Electronic device


FAQ - OBDeleven Open Box Review
https://www.ttforum.co.uk/forum/viewtop ... &t=1926899
OBDeleven

Note -
The FirstGen device (white) is compatible with Android and Harmony. The NextGen device (black) is compatible with iOS, Android and Harmony.

Both the FirstGen and NextGen versions support Audi, Volkswagen, Seat, Škoda, Lamborghini and Bentley. However the NextGen will support more car brands in the future. The functionality of both devices is the same.

Be sure to keep an eye out for discount pricing as OBDeleven often has special deals if you buy directly from them. While resellers like eBay and Amazon also offer the OBDeleven, there have been reports of them selling used devices.

Update -
To avoid the annual subscription fee don't buy the Pro Package and just start with the basic OBDeleven. Then later on after using it a while, if you feel the basic version doesn't meet your needs, you can easily upgrade to the Pro Package and then pay the annual subscription fee at that time.

Pros:
• Android & iOS
• App-based for Smartphone/device
• Price
• Size (OBD dongle only)
• "One Touch" Apps for coding changes
Supports VAG software
• Free updates
• Unlimited vehicles
• Available as FirstGen and NextGen

Cons:
• Pro Package has an annual subscription fee (effective 16 June 2021)
• Requires "Pro Package" upgrade for improved access
• Not all Adaptations and Basic Setting are functional or compatible with all vehicles
• Requires internet access to work (not stand alone)
• Limited technical support


3. XTool V401
Xtool.JPG

FAQ - XTool V401 Code Reader
https://www.ttforum.co.uk/forum/viewtop ... &t=2012963
XTOOL Authorized Dealer

Pros:
• Price
• Hand held, stand alone device (with cable)
• User manual included
• Unlimited vehicles
Supports VAG software

Cons:
• Lack of customer support
• Last software update Rev (7.1) 2013
• Limited Adaptations & Basic Settings
• Can not show when a fault occurred
• No file output capability

4. Carista
Eye Product Liquid Rectangle Gadget


FAQ - Carista
https://www.ttforum.co.uk/forum/viewtop ... &t=2013801
Carista OBD2 App | Diagnose, customize and service your car

Pros:
• Android & iOS
• Price
• Size (OBD dongle only)
• Unlimited vehicles

Cons:
• Subscription based user fee
• Does not have all Adaptations and Basic Setting functions
• Requires internet access to work
Generic OBDII code reader not coded specifically for VAG software
• Limited technical support


VCDS & OBD Definitions

VCDS
is an abbreviation for VAG-COM Diagnostic System, also known as VAG-COM which is a Microsoft Windows-based software package developed and produced by Ross-Tech.
VAG is an abbreviation for Volkswagen Audi Group.

Unlike generic on-board diagnostics (OBD-II or EOBD), VCDS uses the more in-depth VAG-specific manufacturer protocol commands which allows the user to access all diagnostic capable vehicle systems - even in vehicles which are not covered by generic OBD-II/EOBD

On-board diagnostics (OBD) is an automotive term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle sub-systems.
 
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#2 ·
Looking Up Fault Codes -

To understand what a fault code or Diagnostic Trouble Code (DTC) actually means, you can run a Google Search for "Ross Tech XXXXX" where XXXXX is the fault code. This will bring up a link to Ross Tech's wiki which will describe the fault code, possible causes and solutions. While Ross Tech has most of the VAG DTCs, they don't have all of them.

• This link will provide additional information about how fault codes are defined under SAE.
• This link has a complete list of all VAG fault codes.

If you do own a legit Ross Tech VCDS, you can also look for help in the Ross Tech Forum. and run a search for the fault code there. Hopefully some else has run into the same issue and their solution may be applicable even if it's a different model. Otherwise, you can look through this website.

Rectangle Font Screenshot Parallel Magenta

Rectangle Font Parallel Screenshot Software

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Looking Up Fault Codes with OBDeleven -

For OBDeleven owners you use the Lookup feature. Simply click on the Index in the top left of the screen. Select Lookup and enter the fault code. This will provide you with a very simple explanation of what the code means. While useful, it's not particularly helpful so you will probably want to look up the fault code on the Ross Tech wiki as described above.

Font Screenshot Software Technology Multimedia



Common Fault Code Comments -

From Ross Tech -

Intermittent means the condition that set the fault code did not exist (or could not be detected) at the time the scan was performed. Basically, a fault was reported, but when you ran the scan, those conditions no longer existed.

Fault Frequency shows how many times the conditions that caused the fault have recurred, during all driving cycles*. So, if you have a fault with a Frequency of 11, then conditions sufficient to trigger the fault have happened 11 times since the fault was stored.

* A drive cycle usually starts with the ignition being switched on and ends with the ignition off AND the drivers door opened.


For more information on fault codes and how to understand how they work, take a look at the Ross Tech Forum post below -


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#3 ·
The Diagnosis Process

The use of an OBDII diagnostic device is just one step when diagnosing what is wrong with your vehicle.

The first step when running a fault scan is to clear all faults that are present. Then take the vehicle for a drive and run the fault scan again. Any faults that appear this time should be investigated.

All problem diagnosis deal with symptoms that could be the result of many different causes. For example, multiple DTCs reported across different and seemingly unrelated Addresses may may indicate a broader systemic problem. Low voltage will often result in multiple DTCs. However multiple DTCs reported in a common Address (fuel system) does not necessarily mean all the reported sensors are faulty.

For example, if the MAF is defective, it may result in an incorrect air-fuel mixture. The result of an improper air-fuel mixture can then trigger a DTC from the Oxygen sensor which is operating correctly. The wide range of possible solutions must be narrowed down to the actual cause.

The attached PDF goes through a very extensive description of how a successful diagnosis should be performed.

These steps include -

1.) Verify the Problem
2.) Perform a through visual inspection and basic tests
3.) Retrieve the diagnostic trouble codes (DTCs)
4.) Check for Technical Service Bulletins (TSBS) Forum link here.
5.) Look carefully at scan tool data
6.) Narrow the problem to a system or a cylinder
7.) Repair the problem and determine the root cause
8.) Verify the repair and clear any stored DTCs

Credit to pearsonhighered.com for this document.

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