HP Color Laserjet Pro MFP M477fdw 51.23 Error

[real-napster]

Hello,

I have replaced the black laser scanner unit on my laser printer and am now getting a 51.23 error. 

I have tried powering off and leaving it for a while. This didn't work. I have checked the ribbon cable and all connections.

Any other ideas or help would be much appreciated.

Thanks.

[Repairatrooper]

Did you install a new scanner or a used one? Were you getting the same error with the old scanner?

[real-napster]

I installed a used one, but the error are on both - myne and the used one i bought.

[real-napster · Accepted solution]

I have fixed the error. I had previously watched many YouTube videos on this topic, but they were all about similar models, not mine MFP477. What wasn’t shown in the videos, I found in the following forums post: Re: Error message 51.23 51.22 - HP Support Community - 974431

There, I discovered that the laser unit has a shutter (for safety reasons) that only lifts up when the front cover is closed. For this to work, the metal spring on the NFC module must be placed over the shutter, otherwise, the mechanism won’t function properly.

In my case, the shutter was always down or closed, so the laser couldn’t calibrate. Now everything works again.