I don't have the answer to your question, but I have a similar problem and have tried a number of things. My Accord V6 is a 1996 and the same tachometer problems have been appearing and disappearing for about one year. Even the Honda dealership couldn't fix the problem. They have changed the plugs and rotors and the ignition kit. Unfortunately, whenever I try to bring the car in, it runs fine. Let me know if you get a fix.
It could be a bad cap, rotor, pickup coil/reluctor, or a loose ground.
The 2011 Honda Accord has an inline 4 engine.
The 2005 Honda Accord has an inline 4 engine.
The 2004 Honda Accord has an inline 4 engine.
The 2007 Honda Accord has an inline 4 engine.
The 2006 Honda Accord has an inline 4 engine.
The 2003 Honda Accord has an inline 4 engine.
The 2014 Honda Accord has an inline 4 engine.
The 2008 Honda Accord has an inline 4 engine.
The 2012 Honda Accord has an inline 4 engine.
The 2001 Honda Accord has an inline 4 engine.
The 2009 Honda Accord has an inline 4 engine.