Originally Posted by ATG
Or does the ECU only detect the unplugged actuator?
ECU only records the unplugged actuator. This is because youre breaking the electrical current to that solenoid telling it that theres a problem with it, ergo storing a code. However, if you just plug up the line with the BB or pellet or whever, it doesnt see it as a break in current, probably doesnt even know if its open or not. Its the vacuum that closes and opens the valve.