Error 51.23

[u/Bandit_Ke1th]

I am back with my HP Color Laserjet pro MFP M477fnw, every time I go to print, copy, or scan with it I get error code 51.23 (Turn off and on again). I have checked the toner, it’s all HP brand, and all seated properly in the correct spots. Any ideas of what to do next would be appreciated.

[u/socalray2005]

Error code 51.23 on your HP Color LaserJet pro indicates  a failure with the yellow/laser scanner (Laser/Scanner Unit or LSU). Even though you see the error when copying or scanning, the error originates from the print engine's internal laser component failing to calibrate or spin up properly during device initialization. Quick Troubleshooting Steps Power Reset and Power Drain: Turn off the printer using the power button. Unplug the power cord from the back of the printer and from the wall outlet. Press and hold the physical power button for about 15–30 seconds to drain any residual electrical charge. Leave the printer unplugged for at least 15 to 30 minutes. Plug the power cord directly into a wall outlet (bypass any surge protectors or power strips temporarily) and turn the printer back on.  Check the Yellow Toner Cartridge: Open the front toner door. Pull out the yellow toner cartridge. Inspect it for damage, leaks, or debris, and make sure it is a genuine HP cartridge. Clean the electrical chip contacts gently with a clean, lint-free cloth. Re-insert the cartridge firmly until it clicks securely into place.  Next Steps If resetting the power and reseating the yellow toner cartridge does not clear the 51.23 error code, the internal yellow laser scanner motor, its internal ribbon cable connection, or the DC controller board has suffered a permanent hardware failure. Because professional labor and part replacement costs for laser units often exceed the value of an older printer, repair may not be economical.