Codes vs Diagnostic

There is a hug difference between "pulling codes" and actually diagnosing what exactly has cause the code to set. When the computer sees a fault with a sensor or system a code or codes will be set. It is up to the technician to inspect the affected circuit or system to determine what the cause is. Most shops will charge about 1hour labor to begin diagnosing a check engine light. Shops that offer free check engine light diagnoses will often times only "pull codes" and give a preliminary diagnoses.