When the car engine was tested, the engine P1374 Code is found. The catalytic converter has an oxygen sensor behind and in front it. When the car is hot and running in closed twist mode, the upstream oxygen sensor waveform reading should alter. There are now 2 main sorts of cylinder deactivation process used, dependent on the type of engine. The engine P1374 code is for the pushrod style which uses solenoids to change the oil compression transported to the lifters. In their collapsed state, the lifters are unable to raise their mate pushrods under the valve rocker arms, consequential in valves that cannot be activated and endure closed.