www.repairpal.com/estimator
You can check the Estimator tool to see if it's listed there.
Otherwise, contacting local shops near you for a real world estimate -- and to have it evaluated to see if you really have to do this work -- is recommended. Here's a link to find a shop near you:
www.repairpal.com/repair-shops
RepairPal Certified shops can diagnose and repair your 2013 Cadillac CTS. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.