This post is here purely to help those who are Googling for a solution to this problem. Everyone else please ignore!
If you have an HP all-in-one 3300-series printer/copier/scanner, and it starts saying “Scanner error power off->power on”, but powering off and on doesn’t help, then you really need this page. Many thanks to all who posted there!
Basically, you power off the printer and unscrew the screw which allows you to remove the small piece of glass to the left of the main scanning glass.
Using some needle-nosed pliers through the opening, grasp the drive belt and use it to move the scanning head across from the right hand side of the scanning area to the left, until it’s right under the opening. At the bottom of the wide slot, there’s a mirror, and it gets fogged up with something.
Shine a good light in there and use dry Q-tips to give the mirror a good clean. Then reassemble everything and turn the printer back on. After a little warm-up, you should get the ‘Ready’ prompt again, and your heart will be filled with joy.
The whole process should only take about 5 mins. There may be other things which cause a ‘scanner error’, but this fixed it for me and, it would appear, for many others.
Only 11 years after my first post on this forum. And now it’s time again to clean the mirror. (It was 12 years the first time.) Some things are simply timeless and I am super pleased to state “Thanks to the original person who posted this repair” a second time.
This 100% helped! The power unplug didn’t do the trick, but removing the screw and cleaning the glass with a microfiber cloth helped. Completely accurate on the short amount of time it took to complete this process as well. Thank you to the original poster!
I bought my HP Laserjet 3330 new in 2002. It has been used lightly until recently when I needed to print a few online manuals that were over 100 pages each. Anyway, the “Scanner Error. Power Off/On” message came on 2 x’s in February and I got it re-started. A couple of weeks ago, the message returned. I found your information, but hesitated to try it until yesterday. I also found the Service Manual online and read through that. THEIR take was to check the DIMM and re-set or replace it. So, I tried your cleaning the mirror suggestion. As others have said, “Who knew” that such a simple step would correct the machine! The Service Manual Parts Diagrams do not even show such a mirror or at least I could not find it. I did have one glitch while waiting for the scanner to move to the right side as part of the re-start. I could hear slipping or grinding sounds. I hand pushed the scanner a bit and it righted itself.
March 28, 2023, when I attempted to make a photocopy, the printer “scanner bulb warming up” stayed on for 10 or so minutes. I pressed the “start/copy” button. I got “Device Busy” message. The printer did not make the copy. I pulled the plug out. Yesterday, March 29, 2023, I plugged the unit back in. Again, the scanner warmed up, re-set itself for printing BUT the scanner started to make the same slipping or grinding sounds as it did on March 23. I pulled the plug again. When I plugged it in hours later, the “Scanner Error – Power On/Off” message returned. None of the buttons worked. Shut it off. Now what do I do?
I forgot to mention. The few days that the printer worked, I was able to print directly from my computer. It is when I tried to make a photocopy using the glass and the scanner, that the machine failed. Are there at least 2 different internal systems for printing in the copier? Maybe I do need to check the DIMM (?) card as the service manual suggests?