I have a kyocera km 2550 copier that suddenly showed a C6400 error and I can't clear it can you help

SOURCE: Kyocera KM 3050 - error C3300

Error C3300 is a CCD Automatic Gain Control issue.

It could be poor contact in the connector terminals from the SHD PWB to the CCD PWB.

It is more likely a defective exposure lamp or inverter board that powers the lamp.

Try lifting up the Document feeder so you can see the optics frame through the platen glass and turning off and then on, the main power switch to see if the green exposure lamp illuminates.

A better, but more complicated way to check the lamp is to enter the service mode and run the exposure lamp test simulation. I will outline this procedure below. BE SURE NOT TO MESS WITH OTHER THINGS IN SERVICE MODE OR YOU COULD RENDER YOUR UNIT COMPLETELY UNUSABLE.

To Enter Service Mode:
Hit the "Status" button

Hit the following sequence on the numerical keypad:
1 0 8 7 1 0 8 7

You should be in service mode.

Use U601 by typing 6 0 1 and then "Start"

U601: Turning the exposure lamps on
Description: Turns the exposure lamp on.
Purpose: To check the exposure lamp.
Display:
CCD: Main Exposure Lamp
CID: Document Processor Exposure Lamp (inside the feeder)
Method
1. Press the start key.
2. Select the item.
3. Press the start key. The selected lamp lights.
4. To turn the exposure lamp off, press the stop key.
Completion
Press the stop key. The screen for selecting a maintenance item No. is displayed.

After checking the lamp(s) operation hit "reset" a few times to back out where you can type 0 0 1 "Start" to Exit Service Mode.

SOURCE: KYOCERA KM-1820 COPIER

follw these steps, it should work
turn off copier.
open top toner cover.
turn copier back on.
when you see message "close top cover" press "system menu" button.
scroll up to "service setting" then press the # button, green "start" button and the "enter" button all at the same time.
then scroll down to "maint mode"
press "enter"
then enter 163
press" enter "
turn off copier then turn back on
close toner cover

you should be back in business

SOURCE: i have kyocera km 1650

press status key
scroll down to service
press enter
press 163
press enter
wait 10 seconds
recycle power

SOURCE: kyocera KM 1525 COPIER Showing C630 error

check the fuser unit thermistor and replace it......

SOURCE: MY COPIER (KYOCERA 1635) DISPLAS ERROR C6050. HOW

C6050 Abnormally low fuser unit thermistor temperature The fuser temperature remains below 90°C/194°F for 1 s. Poor contact in the thermistor connector terminals. Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Broken fuser thermistor wire. Measure the resistance. If it is ∞ ω, replace the fuser thermistor. Fuser thermistor installed incorrectly. Check and reinstall if necessary. Fuser thermostat triggered. Check for continuity. If none, replace the fuser thermostat. Fuser heater M or S installed incorrectly. Check and reinstall if necessary. Broken fuser heater M or S wire. Check for continuity. If none, replace the fuser heater M or S. Code Contents Remarks Causes Check procedures/corrective measures