Once you fix the error, keep it away with these habits:

: If the code remains after a thorough cleaning, check the electrical connectors between the wand and the nozzle for dust or poor contact.

Do not panic. 80% of E4 errors are solved by cleaning. Follow these steps in order.

Ensure the handheld unit, wand, and floor nozzle are fully engaged and making a clean electrical connection.

Assembly order:

: Long hair, threads, or carpet fibers wrapped tightly around the roller.