The Ultimate Guide to OBD Scanners

The only time most car owners experience or learn about the OBD scanner is when that strange malfunction light on the dashboard of their vehicle comes on. Even with this, car enthusiasts still do not know much about the OBD2 system or what it does. Nonetheless, if you are here because you really want to learn about this system that could literally save you time and lots of money, you are in the right place. 

If you’ve ever noticed a nagging light blinking on your dashboard that keeps distracting you from the road, and you are looking for a way to fix it, well, the OBD2 scanner could reset the codes for that particular ECU and restore your car to perfect conditions. So, without wasting any more time, let’s dive right in and find out more about this system, and the device responsible for accessing this system. OBD2 scanner use; they were adopted to create a standardized ECU for vehicles in the United States.

What Does OBD2 Scanner Do?

It’s only appropriate that we start from the beginning to understand where this particular system originated from. This system originated from California, USA, where it was first required for vehicles in 1996 by the Californian Air Resources Board (CARB) for environmental emission purposes. The system was further endorsed by the Society of Automotive Engineers (SAE), and by 2001, it was mandatory for all small vehicles. By 2010, heavy-duty vehicles were also mandatorily fitted with the OBD2 system including Diesel engine vehicles.

obd2 scanner

An OBD2 is basically a built-in diagnostics system in your vehicle. If you have ever been frustrated by a check engine light before, that is a malfunction that the OBD2 scanner can fix. The is also an indicator that usually sits on the left-hand corner of your dashboard screen, this indicator could start blinking if there is a fault in the car. You can then visit a good mechanic who will now use an OBD2 scanner to request data from the relevant ECUs, in order to understand where this problem is actually coming from.

You can also do this by yourself if you have any interest in cars, it can save you money and prevent an unnecessary disassembling of your vehicle. All you need to do is plug your OBD2 scanner to the 16-pin OBD2 connector that usually sits behind the steering wheel (Check for your car specifications), query the CAN-Bus system which will respond with PIDs you can convert to meaningful information on any online converter.

CAN OBD2 Scanner 

If you would remember how we mentioned that the United States government made the OBD2 system mandatory for all vehicles so that government regulatory commissions can monitor emissions, well they realized their mistake and added something called a CAN Bus system which is under the OBD2 system. This CAN become mainstream when automatic cars became increasingly popular, the different ECUs and engine needed to be able to communicate with one another, and that gave birth to the CAN OBD2.

can obd2 scanner

The Controller Area Network (CAN) is regarded more as a communication tool, while the OBD2 system is regarded as high-level protocol, mostly used for diagnostics. The OBD2 is primarily used for diagnostics to send data from your car to you and vice versa with an OBD2 scanner. The CAN however, is more like a communication tool that allows the different ECUs in your car to communicate easily with each other. The CAN was rolled out when the US government recognized its mistake and realized that there should be a communication tool for the engine. The problem with CAN Bus is that it is too rigid and is means for an OBD2 scanner programmer to do some hacking and CAN sniffing to get any data from it. The system is in your car, but the OBD2 Scanner target was to control emissions and for mechanics to run diagnostics.

When you step on your breaks, the CAN is the network responsible for the immediate slowing down of your vehicle, it sends the messages to slow down as first priority. It is a bus system that allows the various electronic units of your vehicle to work together efficiently. The CAN is under the OBD2, but it was introduced in models from 2005, so if you intend using a scanner, make sure it is not one that was made between OBD2 and CAN as it might not support it. 

How To Read OBD2 Scanner Live Data?

how to read obd2 scanner

Due to the rapid growth of technology, we now have wireless OBD2 scanners which will be discussed later on in this article. However, these wireless OBD2 systems do not completely displace the cable scanners, it doesn’t even matter which one you are using. You need to first understand how to read this data to even make out what exactly might have gone wrong with your car. 

Before cheap OBD2 scanners became popular, mechanics used to have to purchase expensive factory tools especially for European shipments. Once you have identified the type of scanner you are using, you can now move on to the next process of determining if your car supports the CAN bus system.

The CAN bus system provides you with over 100 parameters at your disposal but it is only available for CAN bus system supported vehicles, so I’m sorry, this one really depends on your vehicle. The ordinary OBD2 however, looks more like this; SAE J1850 PWM/PWV and ISO 9141-2) with only less than 40 parameters available.

This is why the CAN bus system really beats the OBD2, it allows you to read quality live data including non-engine related problems (ABS) and SRS trouble code. Remember, newer model scanners will be needed to properly collect this data.


how to read obd scanner

When you are reading your live data, the first thing you want to look at is the STFT and LTFT. These are the factors that determine the gauge or fuel trim going into the engine. This is usually represented as a percentage on your scanner, you want to see something in the range of 5-7%. Anything below -10% and more than 10% is bad and could mean a faulty gauge. In a nutshell, you generally want to see round figures less than 10% but nothing below -10%. A lower value could mean that your CPU is trying to make up for a lean fuel trim and you have a ruptured fuel valve or a leaking fuel injector.

It is important that you check your STFT and LTFT before running any further diagnostics. You should also check it in three stages:1. Car Idle2 .At 1500 RPM3. At 2500 RPM

For instance, if the fuel trim is at 15% when the car is idle but adjusts to 5% when you reach 1500 rpm to 2500 rpm, then there is a problem with the lean engine condition when the car is idle. However, if the fuel trim shows a 20% value when idle and maintains this value as you reach 1500 to 2500 RPM, then there is something definitely wrong with your fuel pump.

Engine Coolant

The right figure for this one should be 190 degrees or higher in Fahrenheit when the car is in operation. Anything lower means there is a fault somewhere.

Intake Air Temperature and Air Injection

With an android phone you can actually fetch a lot of data on your intake air temperature. Apps like OBD fusion and Torque can be used to obtain this sensor data. If the engine is not working, the temperature should be around 5 degrees and the air injection should be in open loop upstream mode. However, if it is in working conditions, then the air injection should be in a closed loop upstream mode. Anything other than what I stated here is a faulty Air injector.

Mass Airflow

The mass airflow reading will be displayed in grams per second or pounds per minute, either ways, newer model of vehicles are equipped with MAF sensors with hot wires that calculate the volume of the air. If the wire is faulty, it can cause the ECU to display wrong information.

Manifold Absolute Pressure 

Most vehicles are equipped with MAF, MAP or both. This sensor is responsible for determining the engine load of the car and is usually around 29.6 inches Hg at sea level and normal speed. It sits around 9.6 Hg at sea level if the vehicle is idle. 

Engine Revolution Per Minute 

The Engine revolution per minute is the engine speed of your vehicle. The ECU uses this sensor to stabilize the engine coils and manage the fuel injection.

If you use an automatic transmission vehicle, the ECU also uses the OBD2 RPM sensor to manage gear shifts and torque conversion when you are driving.

Remember not to use the OBD2 system when driving, except there is someone else around to monitor and operate it while you drive to take some motion parameters.

So How to Read OBD2 Scanner Properly?

This is where it gets a bit technical, however, if you pay attention you can actually learn and carry out these diagnostics on your car by yourself. So, this is how you read an OBD2 scanner.

First of all, you want to plug this scanner to your 16-pin connector at the back of your steering wheel. You can then request messages or query the CAN-bus system, the relevant ECUs will respond to your queries with data logs that are compromised of an identifier and your data. In order to request data from your OBD2 system, you need to first be able to request this data from the CAN Bus system. An OBD2 data is split into two, Identifier and data. The data is further divided into Modes and PIDs. Here is an example of an OBD2 query and response for the speed of a car moving at 55km/hr; Query- 7DF 02 01 0D 55 55 55 55 55. The response can look something like this 7E8 03 41 0D 32 AA AA AA AA. There are so many online converter tools on the internet today that can efficiently convert this Parameter IDs (PIDs) for you. 

Will OBD2 Scanner Work on Diesel?

The OBD2 was initially just a system put in some cars in the early 90’s, however, it was made mandatory for all vehicles in 1996. By 2005, all light vehicles including Diesel engines were fitted with this system. So yes, the OBD2 for gas and diesel is pretty much the same like others.

Will an OBD2 Scanner Read the ABS Codes?

obd scanner wifi

Some very good OBD2 scanners including the wireless OBD2 scanner Android and IOS-compatible can read ABS, EFB, SRS and even Oil reset. The ABS issues are not engine-related problems and any good modern OBD2 scanner with ABS (preferably wireless) can read this data effortlessly.

Where to Connect OBD2 Scanner?

You can connect the OBD2 scanner to the 16-pin connector that usually sits below the steering. Most manufacturers hide it a little for obvious reasons, this data isn’t meant for you, but you can really make use of them in solving some car issues without having to tear your car apart.

The OBD2 Socket Pinout

obd scanner pinout

Can OBD2 Scanner Read Transmission Codes?

Most definitely, OBD2 scanners can read transmission code errors. The CAN-bus system is a communication tool that also controls the transmission of automatic vehicles. So, if there is a problem with your transmission, you can definitely find out with your OBD2 scanner.

How to Use OBD2 Scanner Bluetooth?

To be honest, most app developers promise a Bluetooth compatible OBD2 system, but most of them do not work. However, there are a few of them that actually work, here is how you can use an OBD2 scanner bluetooth.

  1. Plug in your OBD2 scanner to the diagnostics 16 pin connector
  1. Turn your car ignition to the 2nd phase without truly starting it
  1. Turn on your phones Bluetooth and scan for available devices, your OBD2 scanner should pop up depending on its name, pair the two the devices.
  1. Go to your preferred Android OBD2 app and connect it to the paired device which is your OBD2 scanner. Now return to the home page of your App to enjoy its services.
obd scanner bluetooth

Can an OBD scanner Reset Codes?

Well there could be some cases where you might want to reset OBD codes rather than troubleshoot them. The OBD2 scanners can do that quickly. There might be some problems that might require clearing of codes for the OBD2 Scanner to work well, one of them is to turn off the engine lights. You can reset these codes with an OBD2 Scanner app available for Android and IOS. 

Will OBD2 Scanners Reset Airbag light?

This is another of the plenty uses of an OBD2 scanner, they can also be used to reset an airbag light. You might have the issue of your Airbag light popping up even when your car airbag hasn’t been deployed, your OBD2 scanner with the help of android apps like Torque or laptop softwares can fix it. The OBD2 scanner SRS transmission (abs) is also responsible for the gear and torque transmission in automatic cars.

Can OBD2 Scanner Clear Codes

Yes, the OBD2 Scanner can clear codes. If you have a nagging check light problem, the OBD2 Scanner WiFi can clear the codes and replace them and return your vehicle to its original state.

How to Use OBD2 Scanner?

You can use an OBD2 Scanner by connecting it to the 16-pin connector that is hidden below the steering wheel of your car, you can find the specific position of your connector with your car manual. You can then activate the OBD2 scanner launch that will communicate with the Can-Bus system of your vehicle. You can use an OBD2 Scanner from your Android phone to efficiently manage the system. 

Can OBD2 Damage ECUs?

This is very uncommon, but in some cases other factors that might not be related to the OBD2 scanner can be the culprit of a murdered ECU. It is however important that you don’t try to update the O2 sensor software or reprogram it yourself, it is better you take it to your manufacturers to carry out this reprogramming to avoid any problems. There have been cases of cars refusing to start no matter what due to a fried or damaged ECU, while there has been no evidential linkage to even cheaper OBD2 scanners, I will advice you to remain very careful when using it, touch and operate only what you know. 

Best OBD2 Scanner Software for Laptop

I have mentioned some of the best OBD2 scanner apps for Android, it is time I tell you some of the OBD2 scanner software for laptops. OBD2 scanner Link errors can be avoided by making sure you use a good scanner and software that is compatible with your vehicle. The OBD2 scanner with mode 6 is the actual test that truly reveals the faults of the vehicle and monitors the readiness test result.


Gone are the days when mechanics will have to pull your vehicle apart to discover what’s wrong with it, and sometimes even after taking it apart, they can’t still find what is wrong with it. Now with your OBD2 scanner Android or IOS phone, you can comfortably check for any faults in your car system even without having to visit the mechanic. All you have to do is to purchase an OBD2 scanner and request for the data or information you want. The CAN system Bus will then reply your query with a response which you can easily convert to readable information on online converters. I hope this article was helpful, enjoy.

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