so it happens when the oil level is high right? is it still throwing a code now?...... there are other parts of the vtec system which can cause it not to come on, like the solenoid(but those are strong) the solenoid filter, the solenoid seal(if you use the vtec too much).... and you were up to normal operating temp when you tried to use the vtec right? Also, if your water temp sensor (the green one) right by the bottom of the solenoid isnt working it wont engage vtec, and if the knock sensor isnt working it wont engage vtec......