An auto-injector for administering a medicament, comprising: - a housing; - a cartridge receiver configured to receive a cartridge comprising a first stopper; - a cartridge comprising a first stopper, wherein the cartridge is configured to be received in the cartridge receiver; - a drive module coupled to move a plunger rod between a retracted plunger rod position and an extended plunger rod position at the end of the injection of the medicament, the plunger rod being configured to move the first stopper; - a resistance sensor configured to provide a resistance signal indicative of resistance against movement of the plunger rod; and - a processing unit coupled to the drive module and to the resistance sensor, the processing unit being configured to: - control the drive module to move the plunger rod towards the extended plunger rod position with a plunger rod speed; - determine the plunger rod position; - receive the resistance signal; and control the drive module to adjust movement of the plunger rod if the resistance signal is indicative of resistance against movement of the plunger rod above a high resistance threshold, wherein the high resistance threshold is based on the plunger rod position, and wherein adjusting the movement of the plunger rod comprises stopping the movement of the plunger rod; characterized in that the high resistance threshold is a first high resistance threshold when the plunger rod position is between the retracted plunger rod position and a first plunger rod position, and the high resistance threshold is a second high resistance threshold when the plunger rod position is between a second plunger rod position and the extended plunger rod position, and wherein the second high resistance threshold is higher than the first high resistance threshold. - a housing; - a cartridge receiver configured to receive a cartridge comprising a first stopper; - a cartridge comprising a first stopper, wherein the cartridge is configured to be received in the cartridge receiver; - a drive module coupled to move a plunger rod between a retracted plunger rod position and an extended plunger rod position at the end of the injection of the medicament, the plunger rod being configured to move the first stopper; - a resistance sensor configured to provide a resistance signal indicative of resistance against movement of the plunger rod; and - a processing unit coupled to the drive module and to the resistance sensor, the processing unit being configured to: - control the drive module to move the plunger rod towards the extended plunger rod position with a plunger rod speed; - determine the plunger rod position; - receive the resistance signal; and control the drive module to adjust movement of the plunger rod if the resistance signal is indicative of resistance against movement of the plunger rod above a high resistance threshold, wherein the high resistance threshold is based on the plunger rod position, and wherein adjusting the movement of the plunger rod comprises stopping the movement of the plunger rod; characterized in that - control the drive module to move the plunger rod towards the extended plunger rod position with a plunger rod speed; - determine the plunger rod position; - receive the resistance signal; and control the drive module to adjust movement of the plunger rod if the resistance signal is indicative of resistance against movement of the plunger rod above a high resistance threshold, wherein the high resistance threshold is based on the plunger rod position, and wherein adjusting the movement of the plunger rod comprises stopping the movement of the plunger rod; the high resistance threshold is a first high resistance threshold when the plunger rod position is between the retracted plunger rod position and a first plunger rod position, and the high resistance threshold is a second high resistance threshold when the plunger rod position is between a second plunger rod position and the extended plunger rod position, and wherein the second high resistance threshold is higher than the first high resistance threshold.