How To Read Live Data From OBD II

What About EOBD?

One of the best features of an OBD2 scanner is that you can plug it into your car’s OBD port and receive various data about your vehicle. You can also make use of its live data feature.

What is the live data feature? This feature gives you quick and precise readings about your vehicle functions so you can check the engine and be alerted of any issues in the car.

The information basically comes from the engine’s sensors and computer.

You will need to know how to interpret the live data that you receive from your OBD2 scanner, though. Don’t worry – we’re here to help. 


How To Get Started

How To Get Started

Before you can start reading and interpreting the live data from your OBD2 scanner, you will need to ensure that you have the right software.

A code reader is required, and this can be downloaded in the form of apps on your Android or iPhone device.

Once you have downloaded the app to your device so it’s ready to use, you must plug your OBD2 scanner into your car’s OBD port and sync it with your phone.

It will be able to start working within mere minutes! 

What To Know About OBD 2 Data 

What To Know About OBD 2 Data

If your car was made in 1996 or later and was sold in the U.S., it will be compatible with OBD2. But, the parameters that you’ll be able to use will depend on the OBD2 protocol of your specific vehicle.

Older OBD2 protocols will offer about 36 or fewer parameters.

More recent vehicles will support the CAN-BUS protocol, meaning that you’ll have up to 100 parameters to use, so this will increase how much live data you’ll be able to gain and use!

This will make it much easier for you to be able to single out faults that are in your car so you can fix them. 

How To Read Live Data From OBD2

Start With STFT And LTFT Data


When you’re ready to start understanding live data from your OBD2 scanning device, you will have access to STFT (short-term fuel trim) and LTFT (long-term fuel trim).

The fuel trim is basically responsible for figuring out how the car’s ECU is controlling its fuel delivery, so it’s important to know how it’s working.

You’ll see that STFT and LTFT get displayed as percentages by your OBD2 scanner. To know if they’re at acceptable levels, they should both be within the range of five percent as you don’t want anything higher than 10 percent.

If there’s a percentage that’s too high, this could signal that the car has problems with its fuel system, oxygen sensors, injectors, or mass airflow sensor.

If the numbers are much lower than five percent, it could be that the car is battling with a ruptured fuel pressure diaphragm, a leaking fuel injector, or a fault in the EVAP system. 

Check The Engine Coolant Temperature

You want the engine coolant temperature of your car to be 190 degrees Fahrenheit or even higher when your engine is at its best operating temperature.

If it’s lower, the ECU will increase its idling speed to make up for the motor being too cold to perform.

You will see engine coolant temperature displayed as ECT in your OBD2 scanner, with the degrees of the temperature in brackets next to this code.

What About Mass Airflow?

The mass airflow sensor reading will show up as grams per second or pounds per minute. These sensors have a hot wire that works out the volume of air. If the wire’s damaged, it will cause an inaccurate reading.

Note that if you receive a P0101 code on your OBD2 scanner, this means that your sensor isn’t working properly.

A healthy MAF reading should be two to seven grams per second at idle and it should be between 15 and 25 grams per second at 2,500 RPM, but the number will depend on the car’s engine size.

How To Read The Manifold Absolute Pressure

This is another sensor that’s used by the car’s ECU to determine the engine load.

It usually has a reading of 29.6 inHg at sea level when the engine’s not running and 9.6-inches inHg at idling speed.

Don’t Forget About RPM 


When checking your car’s RPM, you want to do so when the engine is idle.

This speed should be between 600 and 1,000 RPM, but if yours is outside of these ranges then you could be dealing with a faulty or carbonated idle control valve, a vacuum leak, or an electronic throttle body

Check The O2 Sensors

These are used by the CPU to control the mixture of fuel that’s in the car motor. Live data from these sensors will give you an indication of the condition of the vehicle’s catalytic converter, and the information will show up in the form of voltages.

These sensors need to have more than 0.8 volts and drop to below 0.2 volts, and they should do so quickly when you step on the accelerator of the car.  

Understand Intake Air Temperature

The intake air temp data informs you of what temperature the air is when it enters the engine.

Your car’s engine system requires this information so that it can calculate the right mixture of air and fuel for the car.

The sensor should read a temperature that’s pretty much the same as the air temperature in the workshop.

If it’s very different, you could have a problem with acceleration, bad fuel economy, and/or an ineffective blend of air and fuel. The intake air temperature will show up on the live data as IAT. 

What If You’re Receiving Codes You Don’t Understand?

What If You’re Receiving Codes You Don’t Understand?

Some OBD2 scanners will have a feature included that enables you to gain information about what the codes mean.

But, if this is not the case or you’re getting a code you don’t understand, you’ll have to look it up online.

If you’re in the market for an OBD2 scanner, it’s therefore important to find one that offers those code definitions.

However, as mentioned, you can also look up any code you don’t understand online to get the information.

It’s really worth taking the time to learn about the codes and what they mean as this will increase your car knowledge and help you diagnose problems in your car. 

How To Get Accurate Readings From Your OBD2 Scanner 

An OBD2 scanner is useful, but in order to ensure that the information you’re receiving from your OBD2 scanner is as precise as possible you need to follow some important tips.

These include the following:

Choose A Compatible OBD2 Scanner


Right off the bat, you have to have the right OBD2 scanner before you can think of reading live data from it.

You can find a variety of OBD2 scanners on the market, and some are more suitable to specific vehicles than others.

It’s essential to check that the scanner you want to buy is compatible with your specific car make and model.

Connect It Properly

To connect your OBD2 scanner to your car so it can start scanning it for data, you’ll need to insert it into your car’s OBD port.

However, there are scanners that enable you to connect them to your car via Wi-Fi or Bluetooth.

Get Your Car At The Right Temperature

You want your car to reach a certain temperature before you start scanning it to retrieve live data. You should aim to get your car to a temperature of at least 180 degrees

Fahrenheit before you go ahead and connect your OBD2 scanner to it. This is important because it will also warm up the sensors from which you will be able to gain the information you need. 

Related Questions 

When did OBD2 become mandatory?


This happened in 1996, so all cars that were made in that year and in later years will have OBD2 on board.

What is a warm-up cycle?

This is when you start the car’s engine and drive it enough so that you can increase its coolant temperature by at least 40 degrees Fahrenheit. 


If you have an OBD2 scanner it can help you a lot when it comes to figuring out if your car is healthy or if there are repairs that need to be done.

In this article, we’ve looked at how to read live data that’s collected by your OBD2 scanner as well as provide you with tips on how to ensure that your OBD2 scanner performs at its peak.


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