The other day I was driving and all of a sudden my 02 civic ex 5speed went into limp mode. We have checked things like the vtec solenoid and other sensors but the car still stays in limp mode. It throws a check engine light instantly and the key light above the check engine light just sits there blinking and my tack does not work either. 5 mechanics and a few friends have looked at it and they can't figure anything out. We then tried running a diagnostic on it, but when we plug it in to try to pull codes nothing even comes up, it does not even recognize that anything is plugged up. This is driving me crazy. Give me ideas on what to do I will try anything to get my car back to working properly.

 

Sounds like the Multiplex Control Unit (MCU). Try resetting the ECU first: With the ignition OFF, remove fuse #6 in the under-hood fuse/relay box for ten seconds. If that doesn't work and you want to diagnose the MCU then PM me as it's pretty involved.