How to use your phone to diagnose your car’s ‘check engine’ light

Car problems are never fun.

But information is power and can mean the difference between having your car sit off the road for several days while you await repairs, or possibly being able to make a quick repair yourself and get back on the road quickly.

Modern cars are good at knowing when something is wrong and will usually turn on the dreaded check engine light to warn you.

But what makes this light shine?

Now you can find out before you even go to the mechanic. With the right tool, your smartphone can talk to your car and let you know.

Enter the BlueDriver Pro.

note: I’ve had my BlueDriver dongle for a few years and the newer versions look a bit different but functionally they’re the same.

This is a tiny Bluetooth dongle from Lemur Vehicle Monitors, an OBD2 diagnostic scan tool and code reader that plugs into the vehicle’s on-board diagnostic (OBD) port and is used to read fault codes as well as view live -Data about your vehicle’s engine and transmission can be used, and other systems.

The process is really simple.

You buy them BlueDriver Dongle, download the app for iOS or Android, pair it with your smartphone, then plug it into your car’s OBD port and start reading data.

The first hurdle many people face is finding their car’s OBD port. It is usually located under the dashboard or glove box.

If you can’t find it, you can search your user manual or Google for the answer.

Here I connect the BlueDriver to a 2021 Kia Stonic. This car has no issues (currently!) but I will use it as an example for this review.

First I play “Hunt the OBD port”.

There it is!

With the found port I connect the BlueDriver to the port.

Now I can switch to the app and start collecting data.

Live data can provide access to a wide range of information about the vehicle’s systems.

The app allows you to graph the data in a variety of ways.

If the car’s check engine light is on, the BlueDriver software can show you the fault code and also give you information about when the car issued this warning, called freeze frame data – valuable information when trying to diagnose a problem.

A powerful feature of BlueDriver Pro is that you get free updates and don’t have to pay a subscription to access your car’s information.

You can also access repair reports detailing potential error code fixes, but this feature doesn’t appear to be available in the UK so I haven’t been able to test it, although here is an example of the report generated. (PDF)

A BlueDriver dongle can also give you information on how to reset the oil gauge on your dash (after you’ve changed the oil, not just to turn off the gauge!), reset the tire pressure monitoring system (TPMS), or reset the battery light.

Oh, and don’t forget to unplug your BlueDriver when you’re done!

I have access to several different car scan tools and I often choose Lemur’s BlueDriver. It’s quick and easy to use, and I can keep it in the glove box ready to diagnose any problems I run into in my car or for my friends and family.

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