DTC P1607: Powertrain Control Module (Pcm) Internal Circuit Failure
WARNING: This page is about a different car, the 1998 Acura Integra. However, it is still accessible from the selected car via links, so may be relevant.
Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING CODES under SELF-DIAGNOSTIC SYSTEM. Start engine and allow to idle for 5 seconds. If DTC P1607 does not reset, problem is intermittent. System is okay at this time. If DTC P1607 resets, substitute a known-good PCM and recheck. If symptom or problem goes away, replace original PCM.