Why has my s60 gone into limp mode?

Your S60 may have gone into limp mode due to a variety of issues, such as a malfunctioning sensor, a transmission problem, or an engine fault. Limp mode is designed to protect the engine and transmission from damage by limiting performance. Check for any warning lights on the dashboard, and consider running a diagnostic scan to identify any trouble codes. It's advisable to have a professional mechanic inspect the vehicle to diagnose and resolve the underlying issue.