"Incompatible Fuser Unit" error message HP LaserJet M601
Is there any troubleshooting on this?
If you are seeing the message "Incompatible Fuser Unit" on your HP LaserJet M601, M602, or M603 series printer, you probably have the wrong model fuser installed in your printer. (The fuser is the consumable part in your printer which heats up and bonds toner to the paper.)
The problem is, HP makes 2 different model fusers that look very similar -- the P4015 series fuser and the M600 series fuser. Because of the similarities in appearance, sometimes the wrong fuser gets installed in the wrong model printer.
The easiest way to check which model fuser you have installed is to pull the fuser out of the printer and look at the fuser's barcode. It is easy to remove the fuser on these models; if you don't know how to remove your fuser see the removal instructions farther down this page.
Once you have the fuser removed from the printer, look at the barcode as shown below to determine which model fuser you have installed. For the M601, M602, M603 series printers the fuser part# should read RM1-8395.