Lexmark Optra C710 Service Manual - Page 118

5016-001 920 and 921 Error codes. FRU 1 Thermistor 2 Engine Board HCU Cable Action Be sure the thermistor is clean and positioned properly. Check the following resistances of the thermistor: • Hot: (CN18-1 and CN18-2) (engine board) should be approximately 2.0 - 2.5 k ohms. • Cold: Should be approximately 150k to 250k ohms. If incorrect, replace the thermistor. Check the HCU cable and fuser to engine board cable, to be sure the contacts in the HCU cable (the autoconnect) are not bent or damaged. • If damaged, replace the HCU cable. • If the no damage is detected, be sure the cable is installed correctly at CN18 on the engine board. If the cable is good, replace the engine board. Error codes 923 and 924 may display for a hot fuser failure. . 2-52 Service Manual