The manufacturer of an automobile is required to provide access to data to facilitate the repair or maintenance of your vehicle. This may include diagnostic trouble codes, data to calibrate a part or identify the required replacement parts, etc.

If you are dealing with a mechanic that is independent of the manufacturer, the manufacturer must provide them with access to the data.

Recourse options 

Does the manufacturer refuse to provide you with access to the data? Or to the repair shop you are dealing with?

First, try to reach an agreement with the manufacturer. The section titled Resolve a Problem With a Merchant presents the various steps to achieve this. If the negotiations fail, you can send the manufacturer a formal notice and, ultimately, file a claim in court.