Abstract: A method and apparatus for detecting the end of life of a print cartridge for a thermal ink jet printer determines the status of the print cartridge and warns the user if the print cartridge is at or near the end of its useful life. In a first mode of operation, an initial temperature of a printhead contained in the print cartridge is checked after a threshold amount of ink is expelled from the printhead, such as for a high density print swath or during a service routine. This initial temperature is then compared with a maximum initial temperature. If the initial temperature exceeds the maximum initial temperature, a warning about the status of the print cartridge is sent to a user. If the initial temperature does not exceed the maximum initial temperature, the user is informed of the remaining life portion of the print cartridge. In a second mode of operation, a final temperature is checked after a period of time elapses since the threshold amount of ink is expelled from the printhead.