Hi all, having fun with arduino i hope you are as i have been. 
Here's a little project ive been working on for some months slowly.
It monitors (in my case) coolant temperature, oil pressure & coolant level, using your existing engine sensors, (except coolant level, i had to add float switch)
If any are incorrect, an alarm is raised, giving you as much notice of your engine's impending doom, and hopefully enough time to shut it down before damage.
Source code, more details and photos here:
my next goal is to make a pcb for it
Oh, and before you jump in with "why dont you just do that with OBD" comment, my engine does not support that protocol