How do you check the obd codes on a checy with a code key?

To check the OBD codes on a Chevy using a code key, first, locate the diagnostic connector under the dashboard, usually near the driver's side. Insert the code key (often referred to as a paperclip or jumper wire) into the correct terminals on the connector to initiate the code retrieval process. Turn the ignition to the "On" position without starting the engine, and watch for the check engine light to flash, which will indicate the trouble codes. Count the flashes to determine the codes, and refer to a code chart for their meanings.