840.02 or 843.99 scanner error code

Issue description

The MFP displays a Scanner Error message. An 840.02 or 843.99 type numeric error code accompanies it.

• 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.

A service call may be required to resolve this issue. Certain rare occurrences, however, such as a power fluctuation or a static discharge near the MFP, can cause a false 840.02 or 843.99 error message to display. In such cases, the error is only temporary and can be easily resolved without service.

Solution

Perform the following steps to determine whether a service call is required:

1. 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.

   Note:  Do not power the MFP off and on too quickly. Doing so can cause a power issue and create this type of issue.



2. 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.

   Note:  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.



3. 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.


4. If the 843.99 error re-appears again, please switch off power to the MFP.



5. Open the ADF front cover and remove the pick roller assembly.



6. 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.



7. Pull up the flap, and wipe the sensor behind it. Close the flap, and close the ADF cover.