Understand the codes you read.

When all of a sudden that most mysterious indicator turns on: "Check Engine", you are cruising down the road.What does it mean?The engine is large and complex, so checking it isn't going to give many answers.There is a code reader that comes in that area.This little device will allow you to see where the error is coming from.

Step 1: Obtain a tool to use.

There are many online and auto-parts stores that sell the readers.You can download an app to interpret the data on your phone and purchase a reader that will show the codes and explanations on the phone.If your car/light truck is older than 1996 you will need to purchase an OBD-I scanner which is more vehicle specific and do not use the universal coding system.The article focuses on the system.The performance of your engine and Emissions Control System is monitored.The Check Engine Light will turn on if the vehicle emissions are greater than or equal to 150% of the Federal EPA mandated limits.

Step 2: The Diagnostic Link Connector is located in the vehicle.

Under the left hand side of the dash is a triangular shaped 16-pin connector.Refer to the owner's manual if you have trouble locating the DLC, or use the internet to find it.

Step 3: There is a code reader in the DLC.

Do not start your engine if you turn your ignition on.The onboard computers in your vehicle will begin to communicate with the scanner.Messages like "searching for protocol" and "establishing data transmission link" can be seen on the screen.jiggle the connector if the screen stays blank and doesn't light up.Older cars may not have the best connections.If you still don't have any luck, make sure your cigar lighter works.The cigar lighter circuit is used to provide voltage to the DLC.If the cigar lighter doesn't work, check the fuse.

Step 4: Your vehicle information can be entered.

The make and model of the vehicle will need to be input on some scans.It is possible that you need to specify the engine type.The process will be different depending on the device.

Step 5: You should find the menu.

Look for a menu when the scanner is done.To open the main codes menu, select "Codes" or "Trouble Codes"Engine/Powertrain, Transmission, Airbag, Brakes, and other systems may be presented to you depending on the year of the vehicle.You will see more than one type of code when you pick one.Active codes and pending codes are the most common.There are active codes that keep your check engine light on.The code setting conditions haven't occurred for two or more operations of the vehicle if your Check Engine Light is off.If the emission control system fails at least once, the check engine light will be turned on and the malfunction will become an active code.

Step 6: You can learn what the letter means.

The code will start with a letter.You may have to move to different menus to see some of the letters.The engine, transmission, fuel system, ignition, emissions, and more are covered.This is the largest set of codes.The body.This includes seat belts, power seating, and more.There is a Chassis.The codes cover a lot of things.Undefined.Other parts of the car are covered by these codes.

Step 7: What numbers mean?

Generic codes P0xxx, P2xxx and P3xxx apply to all makes and models.Honda, Ford, Toyota, etc. are manufacturer specific P1xxx codes.The second number is what the code refers to.The transmission is referred to by P07xx codes.The code refers to a specific problem with the last two digits.You can check a code chart online.

Step 8: An example code is available.

There is a misfire condition on cylinder #1.The 0 and P indicate that it is a generic or universal code.The area is an Ignition System code.There is a misfire condition in the number 1 cylinder, which indicates that it's a cylinder specific problem.It could be that there is a vacuum leak near the cylinder or that the spark plug is worn out.A code doesn't tell you what component is malfunctioning, it only indicates that a component, its circuit, or its wiring/vacuum control are malfunctioning.The code may be a symptom of a malfunction.

Step 9: Make sure your vehicle is functioning properly.

It takes years of training and practice to properly diagnose the codes.A weak battery or worn out alternator can set a number of codes in systems that are not abnormal.Codes alone won't tell you what parts need to be replaced or what repairs are needed.If you don't know what you're doing, you should take your car to an L1 Advanced Engine Performance Diagnostic certified Master Technician.

Step 10: The Check Engine Light should be reset.

If you have made repairs or don't want to see your Check Engine Light for a while, you can reset it using most of the OBD-II scans.Depending on the manufacturer, the light will turn off when the car has been driven for a certain amount of time.The Check Engine Light can be reset from the main menu.It's also called a CEL.