Hey guys, could not find this info anywhere including here, specific to Laserjet 4345mfp, and M4345mfp.

JAMMING:
Jam in Top Cover area, under toner, error 13.0A.00 by itself.
First check the sensors mentioned in service manual, clean if needed. Still not fixed? The 'A' means 'all' it doesn't really know why it's jamming.
Sometimes the entire lower reverse assembly inboard of toner cart needs replacing, but after a couple days of fighting with mine, I realized the return spring on the duplex gate solenoid on this unit cannot return itself when upside down. So I used an ancient analog copier trick, and pulled the end loop off the hook at the frame and hung it by the 2nd coil of the spring from the loop, and VOILA! NO MORE JAMMING! On a side note, if you get blank pages fed from tray 2, it's a different problem, requires removing/de-sticking feed solenoid.

SCANNER INITIALIZING PLEASE WAIT:
Along with the fixes stated on the web, such as formatter connection issue, scanner binding, DC controller connections, there is ONE obscure youtube video where a guy fixed his by replacing control panel, his start button/reset button area was broken from being stabbed 500,000 times by aggressive fingers. It worked to fix mine for a few months, but then I updated firmware on a formatter I bought to try addressing this problem earlier and it CAME BACK! Although it had no message or issue with old 2008 firmware level! It's gone for now but I don't trust it's gone for good.