Hello dtcs are any of the lights of errors that may appear on the body computer and in the instrument panel that is usually detect as well as on the framework in the diagnosis, therefore, many smart to avoid that the customer do the work, not being able to fix a fault eliminated through the elimination of the dtc by masking and then the problem that a car as a result of a modification made evil or a malfunction could have, but sometimes you have to reset the dtc on some ecu specifications that while doing a perfect job on some ecu you have to delete it the same. You have to see in which situations and the ecu and the reasons why sometimes you have to tap the dtc