Kyocera error C7990 - waste toner box full or not detected
The machine has determined that the waste toner container is full or that it cannot detect one fitted correctly, and has stopped to avoid spilling toner inside itself. It is one of the more approachable Kyocera service codes because the remedy is usually replacing a consumable rather than a repair. Colour machines fill the waste container faster than mono ones.
What causes it
- The waste toner box is genuinely full
- The box is not seated correctly or its cap is not fitted
- The detection sensor is obscured by spilled toner
- A replacement box was fitted without the machine registering it
- Heavy colour printing or frequent calibration has filled it early
How to fix it, in order
Work down the list and stop when the printer recovers. The steps are ordered from most likely and least invasive to last resort.
Locate and check the waste toner box
Open the front cover and find the waste toner container, usually a plastic bottle on the left-hand side behind the cover. Lift it out carefully and keep it upright, since it holds loose toner. If it is full, that is the whole explanation.
Fit a new waste toner box
Install a genuine replacement container for your model, pressing it in until it seats fully and any cap or catch engages. Seal the old container with the cap supplied and dispose of it according to your local rules or the manufacturer's return scheme.
Reseat the box if it is not full
If the container has capacity remaining, remove it, check nothing is obstructing its mounting, and refit it firmly. A box sitting slightly proud of its stop will not be detected and produces this code even when empty.
Clean the detection area gently
Look for toner dust on the sensor or the contact face where the container sits, and wipe it with a dry lint-free cloth. Do not use a household vacuum cleaner, since toner particles pass straight through ordinary filters.
Power cycle to clear the message
Switch the machine off, wait a minute and switch it on again after fitting the container. The counter is normally reset automatically when a new box is detected during start-up.
Confirm the part number
Waste containers are model-specific and a similar-looking part from another Kyocera model may not be detected. Check the part number against the supplies list for your exact machine before ordering more.
Stopping it happening again
When it is not worth fixing yourself
If you would rather not work through this alone, a printer specialist can take a look with you on a screen-share and tell you honestly whether the machine is worth saving.
Printers that show this code
Frequently asked questions
Can I empty and reuse the waste toner box?
It is not designed for that, and spilled toner is difficult to clean and unpleasant to handle. Fitting a new container is the intended approach.
Why does it fill so quickly on a colour machine?
Colour machines discard toner during calibration and colour registration cycles as well as during printing.
Is spilled toner harmful?
Treat it as a fine dust: avoid inhaling it, wipe it up with a dry cloth, and use cold water on clothing since heat sets it.
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