How to read engine trouble codes ?

Engine trouble codes (ETC) are automotive computer codes stored by the on-board computer diagnostic system (OBD) in your vehicle. To read the codes, you will have to plug a scan tool or code reader into the 16-pin OBD II diagnostic connector, which is usually located under the dash near the steering column. The tool will then display the code or codes that have turned on the Check Engine Light.

Checking Troubles With OBD Scanner

You will need an OBD scan tool. The scanner allows you to communicate with the computer and retrieve the trouble codes. Certain scanners may give information on what the revealed code means, but most will just give a five digit number and letter combination.

Step 1: Find Your Vehicle's Diagnostic Plug
The one in my car was a small blue plug that was bundled together with another factory plug beneath my glove box on the passenger's side of the car.

Step 2: Bridge the Wires
Get a paper clip or a piece of wire with the ends stripped off. Stick one end of the wire or paper clip in one of the holes in the plug and stick the other end in the other.

Step 3: Watch the Flashing Light and Decipher the Code
With the wire in place, put the key in the ignition and put the car into the "run" position. That's two clicks for Honda users.
At the end, record all the codes given. The "Check Engine" light will display the codes in sequence and then keep repeating them in order. Refer to your repair manual to check for the meaning of the codes.