45762101TH Rev.1 
2-35
2. TROUBLESHOOTING PROCEDURES
(1)  LCD Display Trouble ...................................................................................2-36
(1-1)  LCD displays nothing ...........................................................................2-36
(1-2)  Display of OKI logo ..............................................................................2-37
(1-3)  Error message display .........................................................................2-37
(2)  Abnormal MFP operation after powered on ................................................ 2-37
(2-1)  No operation ........................................................................................2-37
(2-2)  Abnormal sound ................................................................................... 2-39
(2-3) Abnormal odor .....................................................................................2-40
(2-4) Slow starting time.................................................................................2-40
(3) Paper feed jam (Error code 391: 1st tray) .....................................................2-51
(3-1)  Does a jam error occur when turning on the power? ...........................2-51
(3-2)  Jam occurs immediately after the paper feed is started. (1st tray) ....... 2-51
(4) Feed jam (Error code: 380, 381) ....................................................................2-52
(4-1)  Jam occurs immediately after the power is turned on. .........................2-52
(4-2)  Jam occurs immediately after the paper feed is started. ......................2-52
(5) Paper feed jam (Error code 390: Multipurpose tray) .....................................2-53
(5-1)  Does a jam error occur when turning on the power? ...........................2-53
(5-2)  Jam occurs immediately after paper feed is started. 
  (Multipurpose tray) ...............................................................................2-54
(6) Paper running jam (Error code: 381) .............................................................2-55
(6-1)  Jam occurs immediately after the power is turned on. .........................2-55
(6-2)  Jam occurs immediately after the paper feed is started. ......................2-55
 (7) Two-sided printing jam (Error code: 372) .....................................................2-55
(7-1)  Two-sided printing jam. ......................................................................... 2-55
(8) Paper size error (Error code: 400).................................................................2-56
(8-1)  Jam occurs when paper end is located near the entrance sensor. ......2-56
(9) Fuser unit error (Error code: 170 to 177) .......................................................2-56
(9-1)  Error occurs immediately after the power is turned on. ........................2-56
(9-2)  Error occurs approx. 1 minute after the power is turned on. .................2-56
(10) Motor fan error  (Error code: 122, 127, 128).................................................2-57
(10-1)  The low voltage power supply fan does not rotate immediately 
    after the power is turned on. .............................................................2-57
(10-2)  All fans of the printer do not rotate. ................................................... 2-57
(11) Print speed is slow. (Performance is low.) ...................................................2-57
(11-1)  Print speed decreases. .....................................................................2-57
(12) Option unit cannot be recognized. ...............................................................2-58
(12-1)  Option try unit cannot be recognized. ...............................................2-58
(13) LED head cannot be recognized. (Error code: 134) ....................................2-58
(13-1)  Service call 134 (LED HEAD Missing) ..............................................2-58
(14) Toner cartridge cannot be recognized. (Error code: 543)  ..........................2-59
(14-1)  Error caused by the consumable items. ............................................2-59
(14-2)  Error caused by the toner sensor .....................................................2-59
(14-3)  Error caused by the defective mechanism ........................................ 2-60
(15) Fuse cut error (Error code: 153 to 155) .......................................................2-60
(15-1)  Fuse cut error ...................................................................................2-60
(16) Humidity sensor error (Error code: 123) ......................................................2-61
(16-1)  Humidity sensor error .......................................................................2-61
Note! •  When replacing the CU/PU board, please read the content on the  
EEPROM chip of the old board and copy it to the new board. (Refer to 3.6.1 
when exchange the CU/PU board)
  •   Connection  diagram is see Fig1-1.
2.5.5  Preparing for troubleshooting