By actuating of flaps in the intake passage the passage at the inlet valve of the cylinder can be narrowed. This reduces the air flow. The flaps in the intake passage are controlled by the intake throttle actuator. Calculation of the duty cycle for the inlet passage shut-off can be switched on and off by the function switch of the inlet passage shut off. If the engine speed and the demand quantity + low idle governor exceed certain thresholds, also the MAFS signal must be above a threshold. If this not the case, the error "flap blocked closed" is recognized. If the engine speed and the control duty cycle exceed certain thresholds, the digital switch of the inlet passage shut off must be actuated. If it is, the error flap blocked open is recognized. In case of the throttle actuator stuck, the engine symptoms will occur a running engine stall and a starting impossible.

If the intake throttle actuator is short circuit to battery during two driving cycles, this code will be set.