I got a b16a obd0 and its throwning a cel after vtec engages its code 21 vtec soleinod…then i turn the car off and it goes away but once it hits vtec does the same… Read that it could be low oil but oil level is good…
it could be a loose wire on the solenoid or loose ground, clogged solenoid filter. Take off the vtec solenoid and check if its leaking or clogged, buy a new one since its only like $3…
Do what was said above and also check your oil level.