All cars and trucks built after 1995 come with a built-in port called an OBDII.
The OBDII port talks directly to the vehicles computer and when used with a OBD2 scanner tool displays the problem with the engine.
The OBDII port and scan codes are universal across all vehicles so the same P0102 code (Mass Airflow Sensor) on a Dodge will be the same problem on a Toyota.
Most all OBD ports are located under the dashboard on the driver side and simply needs a scanner tool to plug into the connector and decode the codes.
There are many scan tools available from cheap to expensive
For example the low-cost unit Actron CP9125 PocketScan Code Reader which is a good tool for the Beginner.
It is an all-in one unit that can read codes and clear them from most any vehicle built after 1996.
There is also Bluetooth scan tools available that work in combination with a smartphone or laptop and display codes.
These small Bluetooth OBD2 Dongles are good for occasional use and are very low-cost.
Finding out the meaning of a check engine light is an easy do-it-yourself task that most anyone can do.
A scanner tool will be needed with many options available depending on your budget.
If you are on a very low budget keep in mind many auto part stores will run a scan of your vehicle for free.
Be sure to call your local auto part store to be sure but most likley they will offer some type of assistance.
Bluetooth scanner dongles are very popular since they are very low-cost (Often Less than $10 dollars) and when paired to a smartphone or laptop can show the problem with any car or truck.
As always before buying any OBDII scan tool be sure to read the reviews on Amazon, forums, or elsewhere to be sure it is the right fit for you.