DIY Windows

OBD2 & Windows: Save On Auto Repair With Diagnostic Tools

Christian Cawley 22-09-2014

Running a car in the 21st century can be expensive, especially if it is out of warranty. Diagnosing faults can be particularly costly, especially if the repair facility is experienced in upselling to ensure you carry out your repairs with them.


The continuing computerisation of automobile systems The Car Of Tomorrow - Today: Top Tools To Put a Computer In Your Car It is becoming an increasingly popular pastime to add a new element to cars, a new hub for entertainment, GPS and communications. The carputer seems to have been inspired partly by TV shows such as... Read More means that repairs are often like-for-like component swaps (much the same as when repairing a desktop computer), which means the modern mechanic needs good understanding of electrical systems as well as those traditional mechanical components that are still in use.

What all of this means, however, is that you can save money on repairs Something Broken? Learn To Fix Anything With These 4 Websites You can spend hundreds of dollars to have a professional help you out, or you can learn how to fix it yourself for the cost of some tools and a couple hours of work. Read More on expired warranty vehicles be performing your own fault diagnosis using a special USB cable and a diagnostic utility. You can then use this information to trace a fault to a particular component (perhaps a temperature sensor, perhaps the brakes) and arrange the necessary repairs.

Automobile Fault Finding

One of the biggest challenges to car owners in the 21st century is diagnosing faults. As recently as 20 years ago, repairing a car meant finding the problem through a series of checks. Some of these checks might not be entirely reliable and might also necessitate the removal of entire sub-systems, but on the whole it was a simpler process. Cars were largely about the mechanics, which meant no specialist computer knowledge was required.

From around the mid-1990s onwards, this changed across almost all level of mass produced automobiles, and the creep of computerisation and the introduction of sensors and electronic monitoring of components and sub-systems has resulted in a lock-down on what parts can be replaced, and how.



After all, how do you replace a part if you can’t diagnose the fault? Diagnosis these days occurs under the watchful eye of the manufacturer’s team of repairmen, or expensive third parties.

But it doesn’t have to.

What Is OBDII?

Somewhere in your car is an OBDII port, a SCART-style connector that provides a connection to the ECU (engine control unit), and through which diagnostic information (and monitoring data) can be received.



Specification for OBDII states that the port must be no more than three feet from the driver, so look around your gear stick and handbreak, under ashtrays, under the dashboard, etc.

Once found, you can connect an OBDII-compatible diagnostic machine to your car to find the faults. These can be purchased online for around $30 – but a cheaper option to purchase a dedicated cable or Bluetooth device which usually ships with software compatible with your laptop or Windows 8 tablet (such as the Microsoft Surface Pro Microsoft Surface Pro 2 Review and Giveaway Although the Surface Pro 2 might not be the latest and greatest, is it still a good device to get? Read More series).

What this means is that you can repeatedly diagnose problems and monitor your car’s performance! You might even combine it with plans to install a Windows-based carputer, possibly using an old laptop or netbook The Car Of Tomorrow - Today: Top Tools To Put a Computer In Your Car It is becoming an increasingly popular pastime to add a new element to cars, a new hub for entertainment, GPS and communications. The carputer seems to have been inspired partly by TV shows such as... Read More .

Buying An OBDII Connector Cable

Different car manufacturers use differing protocols for OBDII. Although the physical connectors are the same, the wiring will not be the same for all makes of car.



The solution here is simple: make sure the OBDII connector you purchase is designed for use with your car. You can go online to Amazon and eBay to find a suitable connector Easily Find Anything You Want On eBay, Amazon, Etsy, And Craigslist With RSS Do you ever find yourself wanting a hard-to-find game, comic book or electronic part? Manually searching through Amazon, eBay, or Craigslist can waste a tremendous amount of your time – so why keep acting like... Read More , making sure to check in the product notes that it is compatible with your vehicle.

These devices are inexpensive, and as long as you have compatible hardware to run the software, you should be able to diagnose any problems with your car in minutes.

As far as the devices are concerned, however, using a compact Bluetooth OBDII connector is a better option than having cables strewn around the driver’s seat.


Diagnosing Automobile Faults With An OBDII Connector And Diagnostic Utility

To get to the bottom of any faults your car may be showing (betrayed by lights on the dashboard blinking or refusing staying on after ignition) you will need to connect your OBDII device to your computer. The best option for this is with a Bluetooth OBDII device, as mentioned above; just make sure your computer has Bluetooth or you have a Bluetooth USB dongle connected.


Various apps are available for Windows users. You might try the free OBDwiz from to get the basic functionality (they sell a variety of premium alternatives, including a touch-friendly app) such as a graphical dashboard and diagnostic tools.


Logs can also be kept, but remember data collected is only as good as the sensors in your vehicle, so ensure these are replaced when they stop reporting correctly.

Using diagnostics in any of these apps is a case of switching to the correct mode, running a scan and getting the error codes, which will be displayed alongside the explanation of the fault.

Your Diagnosis Is Made – What Next?

Once you have established what the problem is with your car, you can take steps to resolve it. For instance, my 1999 Vauxhall Zafira recently had a fault with the heater. Without the diagnostic software I may have had to replace the entire sub-system rather than just the fan component.

This was a relatively simple fix, however – other problems may require far more intensive work, for which you may consider getting some assistance with if you’re not experienced with auto repairs.

Have you used a diagnostic application and OBDII cable to help repair your car Learn To Diagnose And Fix Your Own Car With These 10 Excellent Websites These days, cars are computers on wheels, but you can still teach yourself to catch fault cues and diagnose problems before you park it in the garage. These ten websites may not make you a... Read More ? Is this something that you might consider trying? Let us know what you think in the comments.

Featured Image Credit: Professional car mechanic working in auto repair service via Shutterstock

Image Credit: Car mechanic with laptop via Shutterstock, OBDII Fault Scanner on a white background via Shutterstock, M.M.Minderhoud, Florian Schäffer

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  1. Standy
    August 9, 2016 at 11:29 am

    There is a solution to access OBD from the remote side. It doesn't work without OBD diagnostic software, but helps to access remote car and read its mistakes just as it had driven to your station
    The thing is - it provides remote access to USB and COM ports.

  2. JohnM
    November 23, 2014 at 11:27 am

    Two Comments:
    1: I had a problem with my car that was causing it to go into 'limp home' mode after 100+ miles of driving. Garage unable to diagnose problem as would not occour even after idling for an hour. I recorded a lot of data about fuel and misfiring problems but no clear root cause for the fault. Eventually garage replaced Coil Packs which should have been done as they were recalled which cured the problem.
    2: Also used mine to reset the airbag system after I removed the front passenger seat to get something large in the car. Only 4 bolts and an electrical connector but I did not realise this would upset the passenger airbag.

  3. rotormasters
    September 26, 2014 at 12:40 am

    nice i tune my car...

  4. hotdoge3
    September 25, 2014 at 6:27 am

    Back to Basics

    In 1996 the EPA mandated that the computer interface for all vehicles sold in the United States meet a common standard.

    And there's the danger of diagnosing from a trouble code and throwing parts at a problem without understanding it.

  5. Andrew
    September 25, 2014 at 2:42 am

    Sheesh, what is this? 2003? Get a OBDII bluetooth interface from Newegg for 10$ Then grab the free (or paid) Version of the OBDII app from the play store. You can drive around getting all sorts of real time feedback from your on board computer, right through your smartphone. I'm no mechanic, but I've saved myself literally thousands of dollars with this 20$ setup.

  6. Robert B
    September 24, 2014 at 9:49 pm

    Hi all,
    I am a retired aircraft mechanic and know both gas turbine engines as well as the regular internal combustion engines so I have a very good knowledge of how they work. One of the things that if you are mechanically inclined and either want to work on your own car or truck today that you need in addition to any code reader is the factory manuals for the car or truck you own. I am not talking about the crap they sell at your local auto parts shop but the official engine, electrical and emissions manual sold and used by the make of vehicle you own, buy the manuals from who makes your car or truck. When I shop for a new car or truck I make sure that the manuals are available for the owners to purchase. If you are really wanting to do all of the maintenance on your own vehicles it may be worth subscribing to the manufacturers service bulletins that they issue for your model vehicle. I have to agree with a lot of the comments posted about the OBD2 scanners and software that it is not a magic wand that will fix everything, however it is a very good tool for giving you the mechanic a good starting place to begin your trouble shooting. If you own your shop manuals and your fault code leads you to believe for instance that you have a bad O2 sensor or what ever your manual will have the actual test to perform on your part or sensor to determine if it is working correctly or not. Over the years I have learned that usually most problems are caused by the most inexpensive and simple part so start from there and work your way up to the expensive stuff. If money is no issue then just replace the entire drive train and forget any trouble shooting and your problems will be solved (just kidding). Be observant and knowledgeable about your vehicle model, if you think a sensor is not working ask your self some common sense questions first, like does this sensor need both electrical as well as vacuum to operate. If it needs vacuum as well then check your vacuum lines for a break or for one that was not reinstalled by a so called professional mechanic. And remember your vehicle was built and the factory shop is staffed by humans, what they know you can learn as well if you are so inclined. The only difference between an amateur mechanic and a Pro is the Pro gets paid, it has nothing to do with how much knowledge the person has and a lot of times you just might know more than the guy you are giving hundreds of dollars to.

    • Tina
      October 5, 2014 at 6:20 pm

      Thank you for those great tips, Robert!

      Love your conclusion and totally agree. That said, I do think that a professional education along with hands-on-work does make a difference. So I would add that before you decide to give someone money to do work for you, make sure they have the education and experience that justifies their pay.

  7. lott11
    September 24, 2014 at 5:19 am

    i use to be a master mechanic for the past 30 years.
    i have worked for Porsche, GM, Mopar, KIA, Isuzu, VW, Toyota, Alfa Romeo, Maserati, Mazda,
    Peugeot, Volvo, Nisan, & Honda.
    And lite the others state it not as simple as you make it out to be.
    Codes are just the symptom of a problem,
    A O2 sensor code means that there is problem with O2, you would think!.
    A bad injector could cause it a bad coil or coil pack, a spark plug, a vacuum hose that is broken,
    or even the O2 heater not working meaning a broken wire.
    If you are not familiar with the vehicle that you are looking at would you know the most common cause.
    It is not the same for a GM, to VW, or even Peugeot.
    On VW under 100,000 miles it more then likely a fuse or bad ground just like most Japanese models.
    On a GM more then likely its a spark plug wire, or bad ground on the coil, or the coil.
    Let say they get the software to read all sensors, how would they know what are the reading for a O2 sensor, are the readings the same at sea level to dose at 754 Feet above sea level.
    Or those and the map sensor or even mass air flow.
    Let s say they get code is for solenoid on the transmission, do they replace solenoids there are 3 to 4 solenoids on the transmission and this is a KIA.
    Dose he replace all solenoids on the transmission, or he flushes the valve body because it gets just gummed up.
    The solenoids will cost $412.00 plus transmission fluid and silicon, flushing that valve body will cost him a bought $242.00 plus tax that will include the labor and fluids.
    A customer comes in says, well the code state this is the problem it is O2 sensor.
    i checked the car and find more them a few problems, that where caused by customer.
    He has modify the hole exhaust system, the Catt is further back, the O2 have broken heater and the other O2 is loose.
    Because the code state it is left O2, so he replaces the right O2.
    I retired do the same reason, plus it is harder to make any money in a dealer ship now days.

  8. RealNeil
    September 24, 2014 at 1:50 am

    I have two new code readers. One in my 2006 truck, and one in my wife's 2007 car. We have saved a lot of money throughout the years with code readers.

    I taught my wife to read codes in her car if it becomes necessary, and she has tools. She knows how to use them as well. (she goes on road trips to visit her family and I want her to be prepared)

  9. petem8
    September 23, 2014 at 6:18 pm

    First up it's a handbrake not a handbreak....

    I am gonna say that Mike M has some very valid points. I am an electronics tech by career and a petrolhead by hobby. OBD and OBD2 grew out of Mandated requirement that as vehicle manufacturerers began using electronic control of the fuel delivery then ignition of their vehicle's engine they for a time used their own software and service tool interface totally alien to the next manufacturer. It meant the on,y place a customer could have his car serviced or repaired was within that dealership chain. Lucky for the consumer this monopoly was considered bad so the shift to standardisation across all makes for interface was called for and the birth of OBD and later OBD2. Unfortunately the manufactures have added more controller units for things like transmission and many cars now run CANBUS a multiple level of network data traffic and again they often develop their own codes for specifics meaning at times you are back needing the support of the vehicle's agent to fix a fault. An Aftermarket OBD2 tool will often only just scratch part of the surface of what is going on electronically in your model car even when it's advertised the tool "knows your car's codes"... Basically if you get into this part of the hobby of owning a modern car do loads of research and look around for Forums for you pride and joy that will offer up experiences experimenting with OBD others have had good and bad.

  10. J V
    September 23, 2014 at 6:02 pm

    I need open source OBD software for my Linux system.

  11. Abhishek R
    September 23, 2014 at 11:54 am

    OFF TOPIC- Assuming that you are the only one who take care of all WINDOWS PHONE matters. Could you please update "best windows phone apps" page, it's showing 404 errors on pictures and in the mean time some good apps have come. So please update them as well.

    Thak you

  12. Mario
    September 22, 2014 at 3:07 pm

    Good information for me, thank you!

  13. Mike M
    September 22, 2014 at 1:58 pm

    Tell someone that just reading the code store & replacing that part is going to fix their car without explaining what a set code means is kind of misinformation and your lack of understanding the system.
    If it was that simple shops wouldn't be spending thousands of dollars on higher end scanners or training to interpret the data. Thats like saying you don't need to go to a doctor, just take your own blood pressure and do a search online to diagnose it.
    An OBD2 code just means that circuit is not functioning within the specs the computer is looking for. It could be the item noted, like an O2 sensor, but it could also be a broke wire, a fuel mixture issue, etc. . What are you going to tell your readers to do if there are multiple codes set? Buy a new car?
    There's a reason some of the big box parts stores quit loaning code readers to customers. They got tired of customers doing what you are recommending and that not fixing the problem and wanting their money back on the parts the purchased. ANd most places won't take electrical parts back and they ended up with an upset customer.
    Enough said. Got to go to work and see how many people are going to call today because their neighbor has a code reader and they googled the code and want a price on replacing just that part and I have to educate them why most likely it's not.

    • Christian C
      September 22, 2014 at 2:13 pm

      Hi Mike, appreciate you taking the time to comment.

      If this was as big a problem as you observe, I feel that there would be a block by the automobile industry on such apps being released. As it is, MUO readers aren't the people you've described in your comment, and I'm sure no one will rush into code diagnosis without exploring the results before making any repairs.

      I should also point out that I've had three separate occasions where I've self diagnosed and repaired individual faults either single-handed or with the help of more mechanically minded friends, so I do feel that there is an element of scaremongering about your post.

    • Randy S
      September 24, 2014 at 12:12 pm

      I agree with Mike, the diagnostic code simply tells you which section of the car to trouble shoot. This code is just the first step in isolating the problem. Critical: there is no such thing as a fault code that tells what part is defective, it only tells the technician what diagnostic procedure to follow!