i have an ls/vtec with a jdm b16 obd0 head. my question is are all vtec solenoids the same, or are there differences between obd0/obd1/obd2?

reason i ask is because i am getting a code 21 and i've searched with no clear answer as to what i can do to eliminate this code. [vtec solenoid valve]

 

might not be hooked up correctly ( loose wire, not in the right ecu pin location, damaged wire grounding out ).

Your screen might be clogged as well.