Prusa MK4 Error Code 17: How to Fix Nextruder Gear Skip

Q: What does Error Code 17 mean on the Prusa MK4?

Error Code 17 on the Prusa MK4 means the nextruder extruder gear is skipping. This means the printer's sensors detected that the drive gear lost traction on the filament, which is usually caused by a clog, debris in the gear, incorrect idler tension, or filament-related issues like moisture absorption or inconsistent diameter.

Q: Why does my Prusa MK4 keep skipping gears mid-print?

Recurring gear skipping mid-print is most often caused by a partial nozzle clog that builds resistance over time, filament that is brittle or moisture-damaged, print speeds or flow rates that are set too high for the material, or a spool tangle creating tension on the filament path. Start by performing a cold pull to clear any partial clog and try drying your filament if the issue recurs.

Q: How do I clean the nextruder gear on my Prusa MK4?

Unload the filament first, then open the idler door on the front of the nextruder. Use a small stiff brush or a toothbrush to scrub plastic dust and debris out of the gear teeth. A short blast of compressed air can help dislodge material packed deep in the teeth. Rotate the gear by hand as you clean to access all teeth evenly. Avoid metal tools to prevent scratching the gear surfaces.

Q: Can bad filament cause Prusa MK4 Error Code 17?

Yes, filament quality is a very common cause of Error Code 17. Filament that has absorbed moisture becomes brittle and breaks or grinds inside the extruder rather than feeding smoothly. Filament with an inconsistent diameter can jam or slip through the gears. Always store filament in a sealed bag or dry box and try drying suspect filament at 45-65°C for several hours before printing.

Q: Do I need to replace the nextruder gear to fix Error Code 17?

Not usually. In most cases, Error Code 17 is resolved by clearing a clog, cleaning debris from the gear, adjusting idler tension, or fixing a filament issue — no part replacement needed. However, if you visually inspect the drive gear and find cracked or missing teeth, or if the gear continues to skip after all other fixes are exhausted, replacing the nextruder drive gear or the full nextruder assembly may be necessary.

Abstract

Error Code 17 on the Prusa MK4 indicates that the nextruder extruder gear is skipping, meaning the motor or gear mechanism is failing to grip and push filament consistently. This typically happens due to a clog, incorrect tension, worn gear teeth, or an issue with the filament itself. Left unresolved, this error will cause under-extrusion, failed prints, or a complete print stoppage.