This product is a consumable and as such has no guarantee, much like tires of a car. If it breaks immediately, it is replaced. 3d Solex however issues a 12 month guarantee. We know how time consuming it can be to change a heater! Warning: May not work in “Olsson Block” clone! The calibre of the sensor holes are sometimes out of spec. They need manufacture to tolerances within 6/100 of a millimeter. If the hole is too large, the heaters will not be able to transfer energy, and burn out very brightly inside your block!