How to repair P1607 code Powertrain Control Module Internal Circuit ... With Devise 7; P1607 CHEVROLET Serial Communication Problem With Device 7 ... p1607 serial communication problem with device 7 My car has the check engine light on. I found out by searching that the p1607 means P1607 Serial Communication Problem With Device 7.. B1604 Malfunction Toyota Scion Xb owners have reported 3 problem..