How OBDII helps you when buying a used car

Editor's note: This post has been updated in March 2020 for accuracy and the latest information.

Purchasing a used car can be a tedious process. The chances that you make a good deal might not be so good. However, if you succeed in it, you can save a lot of money and trouble. Read more about how OBD Auto Doctor assists you to achieve this goal.

But how can you make such good a deal, how can you be sure that the car has real mileage and was properly maintained, for example? Even more, some of the problems can be hidden, such as engine and transmission problems. These hidden problems might not have come out during the test drive. The key to closing the deal successfully is to eliminate these potential problems beforehand.

Reveal the Hidden Problems

First of all, one of the most beneficial means to making a good deal on buying a used car is to reveal the hidden problems immediately. OBD Auto Doctor is the tool for accomplishing this task. With our software, you can verify that the Check Engine Light (Malfunction Indicator Lamp, MIL) is really turned off, thus revealing a broken light bulb, for example.

You can also check that the Diagnostic Trouble Codes (DTCs) were not incorrectly previously turned off without fixing the real problems that caused the issues. The OBD2 software also reports the pending DTCs with a click of a button. A pending DTC is a diagnostic trouble code that is stored permanently only if the fault occurs a certain number of times. A pending DTC indicates a future issue and you should take them seriously when buying a used car. The pending trouble code will remain pending until the fault condition occurs the required number of times. In this case, the DTC will be then stored permanently. A permanent diagnostic problem will light up the MIL and requires you to fix the issue as soon as possible. On the other hand, if the malfunction does not re-occur during a set period of time, the pending DTC will be automatically cleared.

Some interesting OBD parameters when examining a car:

  • Distance traveled while MIL is activated
  • Number of warm-ups since DTCs cleared
  • Distance traveled since DTCs cleared
  • Engine run time while MIL is activated
  • Engine run time since DTCs cleared

Note that the actual list of available parameters is vehicle specific and not every car supports every parameter.

Check the VIN

Secondly, you should absolutely check the car’s history records before proceeding any further. You can do this easily even on-line with Vehicle Identification Number (VIN). The VIN is a helpful identifier in this case, since a VIN is a unique for every car and it specifies the fingerprint of the vehicle. Typically, the VIN can be found by looking at the dashboard near windshield on the driver’s side of the vehicle (refer the car’s user manual for the specific location). You can also fetch the VIN with OBD Auto Doctor, and verify that the car engine has the same VIN as the physical tag. By comparing the physical VIN and the VIN reported by the OBD2 software, you can tell for sure that the car has the right engine in it.





The good and the bad. Reviews.

Editor's note: This post has been updated in March 2020.

I wanted to write few words about the app store (Apple App Store / Google Play) reviews. We’ve been pleased to notice that most of you have been extremely satisfied with OBD Auto Doctor mobile app. But of course there have been a few not so pleasing reviews. We hope that you realize that we have no means to contact you. We don’t get your e-mail address or other details. We’d be more than happy to try to solve any issues that you might have with the software so if you have questions or issues, please contact us using other media.

Please also take into consideration that when you read 1-star reviews from others, they might be devious rivals that want to influence the app ranking. We’ve tested the app over and over again and really believe in it. I suggest that you download the free version to your phone and make the conclusions yourself. I also recommend that you get the version first and try the connectivity with your car. If the free version works, then the paid version will also work and the other way around. We are glad to assist you on any connectivity issues.

If you, for any reason, have issues with the connection, please consider and check the following:

  • have you turned the car key to ON position?
  • is the scantool adapter tested to be compatible? (check here)
  • are you sure your car is OBDII compatible? (check here)

If you have used the software successfully with your car, please leave a positive review because others might find it useful. We are dedicated to work hard and make the OBD2 software work on every compatible car. If you encounter any issues, please don’t hesitate to contact us. We will read and reply to your message.

Okay folks, that’s all about the reviews, hope you enjoy the software!





What to do when Malfunction Indicator Light illuminates?

Editor's note: This post has been updated in March 2020 for accuracy and the latest information.

Check Engine Light

People usually get interested in the On-Board Diagnostics when the Malfunction Indicator Light illuminates on the dashboard of their cars. The Malfunction Indicator Light (MIL) is also known as the Check Engine Light. The purpose of this warning light is to indicate a detected problem with the car and alert the driver about the issue.

The OBD2 system illuminates the light when there is a problem with the car’s engine, transmission or emission control system. The light turns on only for a reason and you should not ignore it. You should always investigate the cause.

What does the Malfunction Indicator Light mean?

The Malfunction Indicator Light can signal three different types of problems.

  • Occasional flashes indicate temporary engine malfunctions. In this case, it is good to be aware of the possible forthcoming issues which can later on turn to more serious ones.

  • The most common case is when the indicator light stays on constantly. It indicates more serious problem that requires action to be taken; the sooner the better. Yet, sometimes the issues aren’t that serious but can affect the emissions of the vehicle, for example.

  • The most serious type of signaling is when the MIL flashes all the time. It is a sign that your vehicle’s engine is misfiring. The issue is a major one and you should stop the engine immediately to prevent serious damage. For instance, it might cause the catalytic converter to overheat and even cause a fire.

N.B. It is totally normal for the light to illuminate for a few seconds when you start the engine. But it should go out when the engine is running.

How to get more information about the issue?

Some of the OBD-II issues are relatively small. Those don’t have much impact on engine operation. On the other hand, some of the issues are major and need appropriate measures to be taken. Unfortunately, there is no way to distinguish between them by just looking at the MIL.

The only way to find out what’s wrong with the car is to plug in a OBD2 scantool. The tool and accompanied software can read the Diagnostic Trouble Code(s) from the system. Every time the OBD system turns on the MIL light, it will also store a Diagnostic Trouble Code (DTC) in the electronic control unit. The DTC will give information about the detected issue.

The OBD2 system can turn the MIL off automatically if the conditions for the problem stop to exist. After evaluating a system or component for three consecutive times without detecting the problem, the light can be turned off. But, usually the light remains on.

What are the next steps?

If you have a OBD-II scantool (for example one with ELM327 chip) and OBD diagnostic software, you can check the reason for the problem yourself. For example, our car diagnostic software can read the DTC code from the car and give you description of the code. Those will guide you towards the main cause of the problem.

With diagnostic software, you can even reset the MIL yourself. It is important to clear the Malfunction Indicator Light after fixing the problem. This is because, for example, the car will fail emissions testing if the MIL light is ON when tested.

To learn more, read our tutorial on How to read the Diagnostic Trouble Codes and Reset the Check Engine Light with OBD Auto Doctor.





Scantool Garage Open

Hello all DIYers,

I’m glad to announce the Scantool Garage open! Welcome to follow the development of our scan tool software, increase your knowledge in the automotive field, and begin your own passage from a journeyman to an expert.

If you are new to OBD2 diagnostics, I suggest that you start with the tour page and try out the neat features yourself.