PIAGGIO 633823 Service Station Manual page 193

MP3 250 i.e.
Injection
With the engine running at idle speed, check that
the voltage oscillates between 0V and 1V
With the throttle valve completely open, the volt-
age is approx. 1V.
During the closing phase, the voltage is approx.
0V.
If the voltage remains constant, the sensor may be
damaged. Remove the sensor and check that
there are no oil or carbon deposits inside it..
INJEC - 41