The engine P0138 Code tells about the car engine problem and it is easy to solve according to proper manner. The car engine can be fixed as the valves of respective cylinder are remained closed by a pair of arms that trade the conservative engine’s roller-type rocker arm. The engine P0138 code is one of these arms what follows the cam profile while the 2nd arm joins to the valves. During usual engine operation the 2 arms are linked by a locking pin. The engine code P0138 is a kind of powertrain problem and it can be easily solved this problem from the car engine.