Thermostat displays E5 and cannot complete calibration of the motorized radiator valve (Eurotronic smart TRV).

Safety: Radiators can be hot. Allow them to cool before working on the valve. Do not loosen water-carrying parts.

• Replace batteries: For Eurotronic smart TRVs (e.g., Spirit, Comet, or similar), install a fresh set of high-quality alkaline batteries, observing polarity. Retry calibration.
• Check mounting: Remove the TRV head from the valve body. Verify that the correct adapter ring is used (e.g., M30x1.5 or specific Eurotronic adapter) and that it is firmly tightened but not cross-threaded.
• Free the valve pin: Gently press the metal valve pin in and out with your thumb or a blunt tool. It should move a few millimeters and spring back. If stuck, carefully work it back and forth until it moves freely.
• Reinstall and recalibrate: Mount the TRV head straight and level, tighten the ring, then start the calibration procedure from the thermostat menu or by pressing the designated button.
• Replace drive unit: If E5 persists and the valve pin moves freely, the internal motor/gearbox may be defective. Replace the Eurotronic TRV head.