Checking the air valve
Start the engine and let it idle, then pinch the bypass hose near the throttle body and check that the engine speed has decreased.
If the engine is not warm and the engine speed does not decrease, check the tightness of the hoses and the condition of the air valve.
If the engine is warm and the crankshaft speed decreases by more than 200 min-1, disconnect the connector from the valve and remove the rubber casing. With the ignition on, use a voltmeter to check the voltage at the contact «GR» connector, which should be equal to the battery voltage. Otherwise, check the appropriate wires and relays.
After disconnecting the connector with an ohmmeter, measure the resistance between the contacts of the air valve, which should be in the range of 30-45 ohms.
Connect the connector.
After disconnecting the two hoses, turn on the ignition and check that the valve is open on a cold engine and closes when the engine is warm.
Switch off the ignition and reinstall the hoses.