The engine P217b code seems a kind of powertrain problem and this problem is necessary to fix. Deactivation of cylinders is understood by releasing a synchronizer pin that generally interlocks the cam follower and rocker arms. The engine P217b code tenacities the synchronizer pin is free using hydraulic pressure which is measured by a devoted solenoid. The catalytic converter has an oxygen sensor is found in front and behind it. When the car is warm and running in locked loop mode, the upstream oxygen sensor waveform reading should vary. Do not use wrong meaning for solving the car engine problem.