What are heat detection sensors and how can they cause a speed error?
It seems that the pilots didn't activate pitot tube heaters but the investigation is not completed yet.

"Pitot tube, also known as Pitot probe, is a flow measurement device used to measure fluid flow velocity."

So detection sensors in your question refer to pitot tubes and failure to turn on their heaters in icing conditions can cause incorrect airspeed indication. This in turn may lead to incorrect decisions from pilots or autopilot.