2-Pack NTC 100K B3950 Thermistor OD3mm Cartridge Sensor 280C for Ender 3 V2 CR10 V6 Review (2026)

Cartridge housing versus glass bead

Unlike a standard thermistor with an exposed glass sensing bead, this sensor is built into a small metal cartridge housing with an outer diameter of 3mm, which is designed to slide into a matching hole in the heater block rather than being tucked loosely into a pocket. That housing makes the sensor considerably less fragile during installation and less prone to the cracked-bead failures that plague bare glass thermistors, since there is no exposed glass tip to pinch or crush while routing the wire. A brass sleeve around the sensing element also improves how quickly it picks up temperature changes in the block, which is relevant for tight PID tuning.

Temperature rating and filament coverage

This sensor is rated to handle temperatures up to 280C, which comfortably covers PLA, PETG, ABS and many nylon printing profiles that run hotter than the roughly 250C ceiling of a typical stock Ender 3 thermistor. That extra headroom is useful if you print a range of filaments and want one sensor that does not need swapping out when you move from a standard PLA profile to a hotter nylon or ABS blend. It falls short of what a PT100 sensor offers for true high-temperature engineering filaments like PEEK, so buyers chasing 400C-plus temperatures should look at a PT100 setup instead.

Block compatibility is the main catch

This cartridge-style sensor is built for heater blocks that already have a 3mm diameter hole for cartridge sensors, which is common on V6 and newer Creality-style all-metal hotends, but is not present on older stock heater blocks drilled only for a bead thermistor pocket. Fitting this sensor into an older block generally means either sourcing a PT100-style block with the correct 3mm hole already machined, or drilling the block yourself, which is not something every user will want to attempt. Checking your specific heater block's sensor hole before ordering avoids ending up with a sensor that does not physically fit.

Wiring and firmware notes

The listing does not specify what connector type ships on the sensor leads, so it is worth planning to either match bare wire ends to your mainboard's terminal style or add your own connector before installation. On the firmware side, Marlin includes a defined thermistor table entry for this type of 100K B3950 sensor, and selecting the matching sensor type in firmware is necessary for the printer to read temperatures correctly rather than defaulting to whatever thermistor type shipped with the stock configuration. Skipping this step typically shows up as wildly inaccurate temperature readings on the display, which is a quick way to confirm the setting was missed before troubleshooting further.

Two in a pack for hotend and spare

Coming as a 2-pack works well for covering a hotend sensor replacement along with a spare on hand, or for outfitting two printers that share the same cartridge-compatible heater block design. Given that a cartridge housing is inherently more durable than a bare bead sensor, buyers are less likely to burn through both units quickly, which makes the pack size a reasonable middle ground between a single-unit purchase and a bulk pack aimed at print farms or shops doing frequent repairs. For a single hobbyist printer, that spare can sit in a parts drawer for months or years before it is ever needed.

Frequently asked questions