Issue description

The
843.99 error
is usually caused by a
dirty
ADF sensor that requires cleaning and maintenance. This error also leads to an
840.02 Scanner Disabled message
.
This issue is usually seen on MFPs that have been installed but
not
used for sometime, or have a
high usage count
on the ADF.
This can also be seen on MFPs that are placed in a location
not
readily accessible and in which dust/contamination can collect and build up on the
ADF sensor
.

Solution

If this is the first time the issue has occurred and the device is displaying an
843.99 error
, power off the MFP. Leave it powered off for
30
seconds or more to clear its memory.
Do
not
power the MFP off and on too quickly. Doing so can cause a power issue and create this type of issue.
If possible, connect the power cord directly into a grounded wall outlet. Lexmark recommends that laser printers must be so connected, with
no
extension cord, power strip, surge protectors, or UPS. For a detailed explanation, click here.
This step is especially important if the error occurs intermittently.
Power strips
,
surge protectors
,
extension cords,
and
uninterrupted power supplies
(
UPS
) can trigger false errors. This is true even if the MFP has worked previously on your surge device. Should wall-connection access be unavailable, confirm that the surge device is switched on and functioning correctly. To verify it is, you can also try plugging another device (a light or a fan) into the same outlet.
Power on the machine and observe the operation.
Did the error message return?
Yes:
Proceed with the steps below.
No:
If the MFP powers up to the
Ready
screen, try printing. Should the MFP now print correctly, continue normal use. Pay close attention to the printer over the next few days, however, to see whether the issue returns.
If the
843.99 error
re-appears again, please switch off power to the MFP.
Open the ADF front cover and remove the pick roller assembly.
Slightly dampen a soft, lint-free cloth with water. Wipe the surface of both
pick rollers
and replace the pick roller assembly. Also wipe the entire surface under the
ADF cover
, including the two small white rollers, separator pad, and wipe the pick pad.
Pull up the flap, and wipe the sensor behind it. Close the flap, and close the ADF cover.