Reading scan tool data

For most do-it-yourself mechanics reading scan tool data is a simple matter of retrieving the code and identifying what the code means.

When your check engine light comes on, and you connect your OBD two scan tool, in most cases you will just be retrieving the code and identifying the system the failure is in. You will also probably be clearing the code and testing the vehicle to see if the check engine light code returns.

If you own a more advanced obd 2 automotive scan tool. You will be able to pull up the data stream and read the scan tool data in real time. See my Automotive scan tool reviews page

obd 2 scan tool example

If the vehicle is cold, you can then start the vehicle and watch the coolant temperature, voltage rise on the obd 2 scan tool. This verifies the correct operation of the sensor.

If the coolant temperature, voltage remains a fixed value, yet the vehicle continues to warm up, you may have a dead coolant temperature sensor or bad wiring between the sensor and the computer.

Reading scan tool data gives you insight on what the failure may be. When your check engine light comes on and the vehicle sets a specific code, you can then pull up the data stream for that system on the obd 2 scan tool.

Just because the computer sets a code for a specific sensor does not automatically indicate that that sensor has failed. More often than not, the sensor is working correctly and making you aware of a problem with the vehicle.

For the above example of the coolant temperature sensor, if we have set a coolant temperature sensor code and when reading scan tool data the voltage increases as the vehicle warms up. The sensor is working correctly.

In this scenario, the code may have been set due to a stuck thermostat, causing an overheating condition. Or even a stuck open thermostat, not allowing the vehicle to reach its proper operating temperature.

Reading the scan tool data

The online auto repair manual will provide step-by-step diagnostic troubleshooting procedures with component location diagrams for that particular failure code.

Using these tools together can save you a lot of time and money in replacing unneeded parts.

The obd 2 scan tool is very easy to use. In most cases you will find the OBD connector just left and below the steering column.

You simply plug in the diagnostic tool and begin reading the scan tool data. Most scan tools come with cd's or manuals to give you a good knowledge base for beginner diagnosis.

obd 2 scan tools have really come down in price. And reading scan tool data has become much easier thanks to the OBD two standardized protocol.

If you learn how to read and use a scan tool on your own car you can use the same exact technique on any car 1996 and up. My advice is to be the envy of your niehborhood and teach yourself how to read scan tool data

Reading through my other pages on my auto scan tool homepage is a great place to start. Help our free website grow with a

Need quick professional answers to check engine light questions?

Ask A Mechanic

Type your question here

 letters left

This next link takes to a few more articles I wrote on the check engine light problems subject. Go from reading scan tool data back to auto scan tool info page