What is the procedure to address the root cause of the check engine light?

Does it make sense to purchase an OBD meter or should some other diagnostic be performed first?

  • 2
    until you pull the code with a code reader there is nothing you can do. Some auto parts stores will read the code for free.
    – Moab
    Apr 5, 2020 at 18:48

2 Answers 2


Many auto parts stores will read the trouble codes for free. They use inexpensive code readers that aren't capable of reading manufacturer-specific codes. But they're free. If you want to work on your car, owning a decent quality scan tool is a very good investment.


For diagnosing an engine light or other dash lights you will need a scan tool to read the code and then from there you usually go on to read live data in the relevant control module and the last step is component testing to test the suspected faulty components.

After this then repair and retest.

When reading a check engine light though you to consider that OBD-2 is a protocol used to access emissions related data and generally you won't be able to read manufacturer specific codes when accessing a vehicle through OBD-2 or other specialised codes from the transmission, airbag, body control etc.

The best scan tool to use is one that can access OBD-2 emissions data and also manufacturer specific data.

When you plug a scan tool into the car your aren't plugging it into the "OBD port" as people commonly say instead this is called the Data Link Connector or DLC which is the port where the scan tool is plugged in to access vehicle data either through the OBD-2 protocol or through the manufacturer side.

Not the answer you're looking for? Browse other questions tagged .