MCU in Modular Bed is overheated #17827 (XL)

What happened?

The Modular Bed Control Unit (MCU) monitors temperature to ensure the printer operates within safe limits. When the internal temperature exceeds a defined threshold, the printer displays a warning "MCU in Modular Bed is overheated. Any higher will result in fatal error".

Error name: MOD_BED_MCU_MAX_TEMP

Error code: #17827 (XL)

How to fix it?

This warning typically appears when the ambient temperature around the printer is too high, or when the printer is enclosed without proper ventilation.

Ensure the printer is used in an environment with ambient temperature below 30 °C (86 °F).
If you're using a custom enclosure, ensure it has sufficient passive or active airflow to prevent heat buildup. Avoid sealed or poorly ventilated designs.
If you're using the Original Prusa XL Enclosure, no immediate action is needed; it is engineered for safe thermal operation. However, prolonged operation in an already warm room can still contribute to this issue.
Allow the printer to cool down: turn it off and let it rest for at least 10–15 minutes before continuing.
Minimize continuous long-duration prints at high bed temperatures, especially in warm environments.

If the issue persists even in a cool environment, contact our Support for further diagnostics, as the internal sensors or electronics may be faulty.

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1 comment

Andy P.

•

Some of the solutions suggested by Prusa to deal with the overheating Modular Bed MCU are really disappointing and puts the responsibility on the user to deal with what really should be considered as design flaws in the XL and the Original Prusa XL Enclosure. Prusa is essentially telling users to avoid using the printer in a warm environment and to avoid long-duration prints with high bed temperatures, which are not unreasonable situations for XL users:

1) Some users live in warmer climates, and are not always able to house the printer in a temperature-controlled environment (such as a garage), and having to wait for cooler ambient temperatures in order to print is very inconvenient and even impossible.

2) Many users use an enclosure in order to print materials that require higher ambient temperatures and high bed temperatures to reduce warping (ABS, ASA, etc.), and large prints that utilize the XL's increased build volume will naturally be longer in duration. Telling the user to avoid long-duration prints defeats the purpose of using an XL, and telling the user to avoid high bed temperatures defeats the purpose of using an XL with an enclosure.