The is the master key to your locked printer. When used correctly, it saves you the cost of a service call and extends the life of your office workhouse. When used carelessly, it can brick your machine or void your warranty.
Resetting the counter is only half the solution. To avoid permanent damage: Canon Mb2140 Service Tool
Using the wrong version of the service tool (e.g., a tool meant for the MB2120 on an MB2140) can corrupt the EEPROM. This makes the printer completely unresponsive—even to power cycles. The is the master key to your locked printer
Because Canon does not distribute it officially, many downloads come from third-party forums. Some .exe files contain trojans or keyloggers. Canon Mb2140 Service Tool