What does this message mean: 231 Fatal error 03

Press "X" to clear the error message.

1. Press the tools button (picture of a spanner).
2. Press "All Settings".
3. Press "Machine Info".
4. Press "Parts Life".
5. Press "#" until the touch screen message changes.
6. Press the colour of the drum that was replaced.
7. Press "Yes".

231 means RFID reader I/F error. 03 means Communication error
between the RFID reader and the tag chip. The remedial measure is to check for normal connection of the antenna cable.

I tried putting 1.5mm of plastic foam under the RFID chip to raise it up in the toner cartridge. This seemed to work.

231 fatal error is telling you that the data from the chip on the toner cartridge is invalid or cannot be read.

This may happen for one of the following reasons:

1)The printer is unable to read the data on toner chip because of toner dust or dirt inside the printer.
Solution: Clean the printer inside, clean toner slot and drum.. See:Clean your laser printer.

2)Either the toner is not an original cartridge, it is refurbished or refilled, or the chip on the toner cartridge is defective.
Solution: replace the toner, or replace the Chip on toner cartridge.

3)The toner sensor in your OKI is defective.
Solution: Call the support number listed on the printer manual to arrange repair.

communication error between
the RFID reader and the Tag
chip... THATS THE CHIP IN THE TONER CARTRIDGE

940: Error
Waste Toner Transfer Error

The transfer mechanism of the
toner duct for ID is not operating
properly.

Check to confirm that the basket
assembly is in position (if it is
engaged with the gear of the
printer).
Check to confirm that the holder
magnet D contains a magnet,
and check the magnetic polarity.
Replace the HAL IC circuit
board.
Replace the duct assembly
toner.

It doesn't sound good, but a trick to try is to unplug the printer to see if that reset the board.

A 'print spooler' is a range of memory either internal to the printer (sometimes called 'buffer memory') or set aside from the RAM in your system. A fatal error normally means the material you tried to print has been lost and must be sent to the printer again. If the error continues to show up, you may have bad printer memory or perhaps the driver software in your system has gotten stepped on by the operating system and needs to be reinstalled. Windows loves trashing files to keep life exciting.
This problem is not related to the drum or toner cartridge.

Replace Toner and Drum clean everything and it should fix ur issue