OBD2 Scanners: Do’s and Don’ts of Using OBD2 Scanners

OBD2 Scanners: Do’s and Don’ts of Using OBD2 Scanners

Cars have become nothing short of computers on four wheels. The on board diagnostics or simply OBD2, introduced in car models as from 1996, has made it a necessity for every car owner to learn about car diagnostic tools.

OBD2 scanners are one of the many diagnostic tools that you can use to know what’s troubling your vehicle. The OBD2 scanner is the standard software that has been mandated by PA for use for all vehicles with an on board diagnostic software. This scanner can monitor the ignition system and auto transmission in modern fuel injected automobiles.

How does the OBD2 Work?

The OBD2 in the simplest language is a kind of monitor sensor that is able to gather data from a car’s engine and also other systems. The monitor can send different commands to the fuel injectors and to the different systems in the vehicles to measure things like crankshaft and camshaft position, air and coolant temperature, engine rpm, road speed, and throttle opening among others.

The OBD2 is a sophisticated software with so many self-checks to monitor and regulate the functioning of your car and in so doing maintain its good health for the longest time possible. This scanner can even self-correct the vehicles ignition and fuel mixture at every crankshaft revolution.  You however need to have an OBD2 scanner to interpret the results from the monitor.

Background on the OBD2 Scanner and its application

Most people enjoy having an OBD2 scanner even when they have no idea of what it does or what to do when the scanner gives them an error. That’s why it’s common to find people panic stricken when there’s a malfunction in the car. It’s as if they always expect that with an OBD2 nothing should ever go wrong with the vehicle.

The first indication of a malfunction is an ignited “check engine light” on the dash. This light, in the OBD2 standard language, is also called a malfunction indicator light (MIL). When that light is on it means there is a certain sensor in the car that has sent an error message to the powertrain control module (PCM) which it can’t decode.

So the PCM is really the one that will illuminate the MIL to warn you that’s there’s something wrong with the vehicle, although even when this warning comes your vehicle will normally still be running well. In fact, the only other thing that might indicate some kind of trouble with your vehicle is maybe an increase in the fuel consumption and power loss.

The PCM will store a diagnostic “trouble code”. This is what technicians normally checked for using different scan tools to know exactly where the problem with the vehicle is.

The OBD2 scan tool was previously only available to professional technicians mainly due to it’s high price. Luckily, the prices became more affordable for ordinary car owners to be able to purchase them.

Today you can purchase an OBD2 scanner model for as cheap as $20 for an extremely basic scanner that will only show trouble codes, to about $4000 for an OBD2 scanner with full features, upgradable gadget with a computer interface and that accepts the use of multiple languages.

Using an OBD2 Scanner

Using an OBD-II scanner doesn’t require any wizardry, gifts or talents. The process is pretty simple, and while different models may give slightly varying instructions, the following is a general process that most models follow.

  1. Turn off your vehicle and plug the OBD2 scanner into the standard OBD II data link connector which can be located under the dashboard on the driver’s side, the left side of the staring wheel. The end of the cable will normally have a 16-pin plug that should give a perfect fit into the cars outlet.
  2. Turn on the ignition key or run the car, whichever is in the manual, and give time for the scanner to initialize. Some scanner models will need you to press a power button for them to begin the initialization process. Again, it’s important to have the OBD2 scanner manual for the specific scanner so you’re sure.
  3. When the scanner indicates that it’s ready, key in all the data that is required. This will mostly include the type, model and make of the engine, VIN and others. You can then initiate a ‘read’ or ‘scan’ of the vehicles diagnostic system. Again for initiating the scanning, some scanner models will have a button for that while there are others that will demand that you go through a series of manuals.
  4. Once the auto scanner completes the scanning process, it will give you a diagnostic trouble code or several codes. You can either write these down, transfer them to your laptop using a USB cable or Bluetooth if your scanner is Bluetooth compatible.
  5. You can then check these DTC codes in the manual to understand what your car is suffering from. Most manuals will only show the basic codes but if you need more enhanced codes you can check for these on the internet because there are vehicle models that will normally have a supplemental set of codes online.
  6. When you have finished recording the error codes, turn off the vehicles ignition and then carefully unplug the OBD2 scanner.

Be Careful When Using the OBD 2 Scanner for Diagnostics Reading

When connecting the OBD-II scanner cable to the data link connector, be extremely gentle. This is because the 16 pins in the plug are extremely delicate and you can easily bend the pins or crack the plastic around the plug if you push too hard.

Always turn the ignition on or have the car running according to the instructions in the manual. Failure to do this might corrupt the scanning software.

It’s also very important that you drive around with the manual for the specific scanner model that you’re using. Fortunately you don’t have to carry a manual copy as you can simply download a softcopy one from the internet and have it on your phone, or carry along the CD-ROM copy of the manual. Most scanners will normally come with both a CD and a paper copy of the manual.

Inspection and Maintenance Menu

Once you’ve reset the MIL, the scanner will give you another option for inspection and readiness. What happens normally is that the PMC will normally be checking your vehicle to ensure that the fault has been corrected once you begin to drive it. The time duration in which you need to drive your car for the PCM to record readiness is mostly dependent on specific vehicle models.

It’s important that once you have interpreted the codes given by the OBD2 scanner tool, you immediately correct the fault or have your car looked at by a mechanic who will be able to correct the fault.

You should then turn the OBD 2 scanner again for I/M readiness.  This is important because in the event that your car goes for an inspection at the DMV or an independent station, the technician will normally test for I/M readiness using their own scan tool.  You certainly won’t get a sticker if your car fails to pass the test.

View Data Menu

Authentic and quality OBD 2 scanners will normally also have another menu for “view data”. This one lets you into the actual numbers being read by the PCM.

You can view data on oxygen-sensor functionality, rpm and engine load, and air and water temperature, among other potential trouble areas for your vehicle.

With this information it’s easier to know the problem with the vehicle and to determine if it’s worth attempting to fix it on your own to save money or if you need professional input for a more permanent solution.

If you have a pro-grade OBD2 scanner model, you will also have a graphics function. This is normally what technicians use to check several parameters while the engine is on.

If you understand how to read the graphs you have more advantage as it will be easy for you to diagnose the problem without the help of a technician.

Is There A Difference Between “OBD2 Reader” and “OBD2 Scanner”?

Most people confuse a code reader with a scan tool. Code readers are mostly less expensive and are used for simpler functions than OBD2 scanners. They’re able to shut off the MIL light and to read basic codes, but will mostly not offer any greater value.

Code readers are more ideal for trouble codes that are of a more “generic” nature. They are however nor capable of reading enhance codes or OEM which are mostly specific to vehicles.  Generic codes are also known as P0 codes, while the enhance codes are called the P1 codes. Enhanced codes mostly change depending on the model year and should be regularly replaced or updated.

The reason why it’s important that you purchase the OBD2 scanning tool instead of a reader is because the scanner can read both codes. There are certain types of faults in vehicles that will set a P0 code and not a P1 code or vice versa. Unless you’re able to read both codes it can be difficult for you to make the right diagnosis for your vehicle.

Also, unlike code readers, scanners are capable of also displaying the readiness status of the car’s OBD2 system monitors. I/M readiness are self-checks that the OBD2 will run to ensure that the vehicle is operating efficiently and that the error code has been cleared.

There are monitors that run each time the car is started while there are those that will only run under certain conditions of operation.

For example the evaporative emissions system monitor (EVAP monitor) also known as the “loose gas cap monitor” will run after a refilling session.

This checks for vapor leaks and may turn on the MIL or “check engine light” when after refilling the cap is left off or not well tightened. This will set the error codes P0440, P0442 or P0445. Another example of a monitor that will run only occasionally is the catalyst monitor that checks the catalytic converter’s efficiency.

The Check engine light will normally be turned off when the monitor senses a drop in efficiency.

What’s the importance of knowing about the readiness status? The readiness status is mostly what is checked at the DMVs office to confirm that your vehicle is in emissions compliance.

This means that if no codes are set (translates to no trouble found) after all the monitors have been run, then your vehicle is running clean and will pass an OBDII plug-in emissions test or a tailpipe smog check.

With a code reader you can easily clear codes and turn off the “check engine” light, but you will however not be able to check for readiness and may fail to get a sticker in case your vehicle finds itself at the DMV’s office.

Ask for Help If You Don’t Understand a Code Given By an OBD2 Scanner

It’s important to have your boundaries set right when it comes to what you can do with your OBD2 scanner.

Most professional mechanics warn that the trouble codes, normally listed as P0 or P1, are not the actual diagnosis of the vehicle. Unless you’re able to decode the error, it’s important that you have your vehicle looked at by a professional.

The trouble code P0131 for example is a general sensor code. What most people will think of doing when they get this code is to install a new sensor with the hope that this will clear the error and turn off the MIL lights. The bad sensor could also trigger a P0301 misfire code.

Sometimes you could have misdiagnosed this trouble code and a new oxygen sensor together with a new sensor socket may not solve the problem. You will know that the problem was not comprehensively solved if after a small spike in the rotational speed of the crankshaft the MIL lights are turned on again.

Don’t attempt to give the same solution that has seemingly failed to an error code that keeps coming on. There are modern vehicle engines and onboard control systems that can only be easily understood by a professional who understands it.

So unless you have the right tools and training to solve a problem, it is wise to have your vehicle checked at the vehicle repair shop. The good thing is that since you will have already identified the problem using your OBD2 scanner, you will know the kind of service you want.

Most professional repair shops will actually give you a discount if you know exactly what needs to be fixed since this will save them a lot of time scanning the OBD2 and reading the codes.

Like a majority of vehicle owners, you will mostly only know how to flush out your car’s radiator or perform a simple oil change. Making an attempt at more complex tasks for example replacing a timing belt when you neither have the tools nor the know-how might just plunge you vehicle into more problems and have it grounded until a professional mechanic can work on it.

Purchase the right OBD2 Scanner

There are lots of OBD2 scanner models in the market. It’s important that you choose the ones with quality standards so that you can maximize their function. Also when shopping around for OBD2 scanners, it’s important that you check one that is compatible with your vehicles onboard diagnostics tool.

Investing in a quality OBD2 scanner is something that you should not debate on. This is because the scanner will save you so much money that it will quickly return back the money you invested in it and even give you profits.

In fact, with a quality OB2 scanner, sufficient knowledge in mechanics, and proper automotive tools, you will be able to save 70 percent plus of money that you would have used on vehicle checks and repair.

There will of course still be specific circumstances that will force you to seek the services of a professional mechanic, but since you will have control over your automobile, these incidences will be greatly reduced.

Tips for Purchasing an OBD2 Scanner

If you’ve made the decision of purchasing an OBD2 scanner then it’s just proper that you purchase an advanced gadget. Apart from the compatibility of the scanner to your vehicles on board diagnostics, the first thing you want to look at is the latest technology in the scanner.

An advanced OBD2 scanner will be very efficient in informing you about the several critical mechanics like service light system, conditioning control, airbag control, and transmission control among others.

Having this information will help you keep your car in good condition and avoid unnecessary calls to the repair shop.

Another factor to put under consideration when shopping around for an OBD2 scanner is how user-friendly the interface is.

A user friendly interface will make it easy for you to operate the device. It’s not really that the interface should be complicated.

A scanner with an interface that’s easy to understand but gives information to entail is actually more ideal.

OBD2 Scanners: Do’s and Don’ts of Using OBD2 Scanners
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23 Responses to OBD2 Scanners: Do’s and Don’ts of Using OBD2 Scanners

  1. Stumbled on this and saved me lot of time and researching finding the right obd2 scanner for our European-Cars workshop. Another top for local mechanics is to attend an auto exhibition show, and see what’s on offer by other companies. Will give you good perspective on markets common obd2 scanners used by competitors.

  2. Thanks. Reading this article, ended up getting Ancel obd2 scanner from Amazon. Product works great. Very simple and easy to use. Very simple to read and erase codes.

    It not only gives you the code it also tells you what the trouble is. I’m not a big instruction manual type, usually only refer to instructions when all else fails, that being said I used this scanner right out of the box without reading the instructions. It is self explanatory and easy to use. If you have a car that is 1996 or newer I highly recommend to others first looking around, consider how many obd scanner options there are on both eBay and Amazon. It is something I recommend you have in every vehicle and would even make a great gift.

    If you can’t fix the problem yourself you can at least know what the problem is when you take it to the car mechanic and you don’t have to worry about the Mechanic ripping you off by telling you there’s something else mulfunctioning with your car.

  3. Tried the Autocom Delphi obd2 scanner and it’s a great budget OBDII scan tool with bidirectional support. I also tried with my newer cars and a 98 Cadillac I wanted to get error codes and it worked great. If you need a simple scan tool that also reads other systems (besides engine/transmission), I then recommend researching for bidirectional scan tools. Those that are not, will only read simply generic OBD2, which are usually identified by their low price.

  4. Got a Bluetooth unit on Amazon. A powerful little device. It let’s you to scan codes, ABS faults, airbag faults, radio faults, body component faults, and likely some others I’m not recalling now. Not only doesn’t let you scan codes, it also gives you a description of the code and some probable causes for it. You could save these descriptions to dropbox, text them, or email them. It also allows you to clear the codes and view live data while the vehicle is Operating. You can see oxygen sensor real-time data, quantity of fuel in the tank, intake air temperature, coolant temperature, mass airflow sensor information, ambient temperature, control module voltage and much more. Depending on the obd2 scanners software, they are small but powerful scan tools. I wish they made a home based model that allowed by directional controls and some more in-depth monitoring.

  5. Just decided to purchase a OBD2 scanner from reading this and realized wish had bought one earlier! The small Autel obd2 unit works great and easy to use on my 2005 and 2008 vehicles. Based on auto parts store scans due to check engine light, I thought I had to do expensive fixing to pass emissions test. I easily cleared the codes with the obd2 scanner and the codes never came back and car passed emissions. The scanner also identified a legit code on another car so I would replace the part and avoid the check engine light. Instruction manual is concise. Identifies codes, clears codes, and shows when car is ready to pass emissions inspection.

  6. Bought Launch X431. It works. Plug it in, and it works. Every time. Without fuss. Just works. Be happy, get code reader. Clears the codes, reads the codes, it’s all no problem at all. Don’t know about other tools here, but in my experience, any obd2 scanner is better then none.

    Considering mechanic charges $70 just to scan the car codes (not including fixing anything). This takes mechanic literally 30 seconds to whip in their OBD2 scanner into your cars port. Get an output. Print it out. And invoice you $70.

  7. Bought the ANCEL AD310. This is an excellent obd2 tool, with many more features than OBD2 scanners costing a lot more. Made it much easier to diagnose my emissions problem, and once fixed, I could safely reset codes.

    You can also see how many of the emission cycle tests are still pending in the onboard computer so you can wait until you have enough completed cycles to be able to pass.

    In many states, if you clear codes and then immediately go for emissions you will be rejected since the computer has not been able to run enough drive cycles, even though the CEL is not illuminated.

  8. Never preferred an obd2 scanner on a laptop, but decided to give it a try. Got TOAD and ELM327 usb. This tool is fantastic! I used it on my car to determine the error codes for the check engine light, and was able to turn the check engine light off with this tool once I knew what was wrong. It was bigger than I expected it to be, being about the size of a computer mouse. I would highly recommend having this as an investment, and knowing yourself what’s wrong with the car; instead of some auto place maybe reading it wrong or making you buy the wrong part.

  9. Decided on TOAD OBD2 scanner. It’s my second code scanner after “Autel MaxiLink ML619 CAN OBD2 Scanner Code Reader +ABS/SRS Diagnostic Scan Tool” from Amazon. It reads OBDII, including CAN format. I’ve only used it once to date, but it told me everything I needed to know and more. The manual that comes with it is very informative, describing not only the codes themselves, but pending codes and monitors. The software and ELM327 device will tell you about all those things, so not only will you know which codes have popped, but which might pop soon. Far more features that the more common orange-colored brand for the price. Highly recommended.

  10. Long story, short version…I have a 2007 Camaro that was due for California reg and smog in June. I went to get it smogged, via obd2 scanner at mechanic, and it failed.

    Guy said drive, drive, drive. Okay. Put some miles on it brought it back and it failed again. I paid the reg fee already just needed the smog to pass.

    Talked to different smog places (they scanned again via obd2), drive drive that’s all I kept hearing because my battery had died before the test it wiped out the drive cycle memory. Looked on YouTube and saw a several about using this obd 2 scanner.

    Took the car out again today and had this plugged in the whole time. Finally after putting over 250 miles on my car the problem light showed the ok signal. Back to the smog shop and showed the tech to check via obd2. He thought this was pretty cool. Smog done! California sucks when it comes to this stuff so now I really polluted the air.

    Hence I recommend obd2/obdii scanner for anyone looking for peace if car will fail or not.

    • Yes never unplug or replace the battery before smog time because it will fail. Been there and done that too. Each manufacturer has a drive routine that must be accomplished in order for all the systems to be ready for smog check. 250 miles was a lot of driving on your part to accomplish this. Once I learned my cars driving needs, I was able to do them in about 30 minutes and drive right back to ththe smog place and have it pass.

  11. So want to read your engine fault codes on your own? Most modern cars (actually since 1996 in USA) have Engine Control Unit (ECU) computers that monitor engine components, and you can connect to the computer through a standardized port called an OBD-II (OBD2) port.

    First determine if your car has an ODB2 port, get an OBD2 scanner, connect to your vehicle and you can read any fault codes to find out what the ECU is reporting. You can easily perform a search on Google of those codes with your car make/mode/year and find out more information about what other’s may have reported as the likely fix for the problem.

    EG: Type in: P02342, and you’ll get tons of forums discussing the error and it’s solutions. Can find on Amazon. Just search for “obd2 scanner”.

    • Yes, totally fine. It’s impossible for ELM327 to do any damage to ECU/car. Haven’t seen a single case like that in 10 years. ELM327 is not a tuner (changes ECU data). It’s only a reader. Hence ECU is totally unaffected by it’s use.

  12. The Launch obd2 scanner’s I found excellent diagnostic scanner tools for use on variety of cars with multiple OEM manufacturer systems supported. But don’t expect the manufacturer systems working on all cars. That’s unrealistic.

    EG: I attempted to seek out a problem on a 2003 Ford’s ABS and got nothing. The light was on but no report about codes for the ABS system or the traction control. It did find an DTCs and shows Reported fixes. I was really hoping it would find the ABS.

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