DTC P1607: Engine Control Module/Powertrain Control Module Internal Circuit Malfunction
WARNING: This page is about a different car, the 2003 Acura RSX. However, it is still accessible from the selected car via links, so may be relevant.
Perform ECM/PCM reset procedure. See ECM/PCM RESET PROCEDURE/CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Turn ignition switch on. Wait 40 seconds. If DTC P1607 does not reset, problem is intermittent. System is okay at this time. If DTC P1607 resets, update Engine Control Module/Powertrain Control Module (ECM/PCM) or substitute with known-good ECM/PCM. If symptom or indication goes away, replace original ECM/PCM.