My civic went into a limp home mode. Cause unknown. Code scan keep showing "no link". Tach stopped working, a/c won't turn on. Car starts but exhaust is rich and no power, trans shifts hard. Any help would be appreciated. Thanks

 

Sounds like an ECU problem. Some civics have a fail-safe circuit that will get you home but nothing else. Would you be able to find another ecu to swap? Maybe test the basics first: fuses, relays, lose connections, etc.