The engine P1387 Code is expressive and it is explained as p for Powertrain Code Problem is related engine, transmission and emissions systems. 1 for MFG – Manufacturer Specific. 3 for IC Module 4X Ref Circuit Intermittent, No Pulses. 8 for Exhaust Gas Recirculation System Valve 1 and 7 for Cruise Inhibit Control Circuit. The valves of respectively cylinder are kept locked by means of a pair of arms that substitute the conventional engine’s roller-type rocker arm. The engine P1387 code is one of these arms follows the cam profile while the 2nd arm joins to the valves. During normal engine process the 2 arms are combined by a locking pin.