Description

Prusa Nextruder Hotend Heatsink — OEM Replacement with Load Cell

This is the OEM replacement hotend heatsink for the Prusa Nextruder — the finned aluminium component that sits above the heater block and dissipates heat away from the cold zone to prevent heat creep. It comes with the integrated load cell that enables Prusa’s automatic first layer calibration system.

What the Heatsink Does

The heatsink is the thermal barrier between the hot melt zone (where filament melts) and the cold zone above it (where filament should remain solid). The fins radiate heat away from the cold zone, assisted by the hotend cooling fan. When the heatsink is functioning correctly, you get a sharp thermal gradient — hot below, cool above — which prevents filament from softening prematurely and causing jams.

When the heatsink is damaged, clogged with leaked filament, or has degraded thermal performance, heat creeps upward into the cold zone. This causes filament to soften too early, swell inside the filament path, and jam — a problem that no amount of nozzle changes, retraction tuning, or temperature adjustments will fix.

Includes Load Cell

The Nextruder heatsink integrates Prusa’s load cell sensor — the component that physically measures nozzle-to-bed distance with micron precision for fully automatic first layer calibration. If your load cell is producing inconsistent readings, first layer calibration failures, or erratic Z offset behaviour, this replacement unit includes a fresh load cell.

When to Replace

Persistent heat creep causing jams above the melt zone that don’t resolve with fan cleaning or nozzle changes, filament leak that has solidified inside or around the heatsink fins and can’t be cleaned, physical damage to the heatsink or fins from a crash or collision, load cell producing erratic or inconsistent first layer calibration results, and as part of a complete Nextruder hotend rebuild.

What’s Included

Hotend heatsink × 1
Load cell × 1 (integrated)

Not included: heater block, nozzle, heater cartridge, thermistor, cooling fan, or silicone sock. These are separate parts.

Compatibility

Prusa MK3.9 / MK3.9S
Prusa MK4 / MK4S
Prusa XL
Prusa CORE One / CORE One+
Prusa CORE One L

Not compatible with the MK3/MK3S/MK3S+ (which use E3D V6 heatsinks), Prusa MINI/MINI+, or any non-Nextruder printer.

Installation

Refer to the Prusa Knowledge Base repair manual for your specific printer model at help.prusa3d.com. Select your printer and follow the hotend disassembly and reassembly instructions. After installation, run a first layer calibration to initialise the new load cell.