The meaning of the U1020 Code is necessary to know if you want to fix the car engine problem. Do not drive the car with any engine problem. You should keep studying the real meaning of the code and if you do not get that real meaning or do not know how to solve the problem, you should not try to fix the problem. The engine code U1020 is the main thing to check the process of the VCT solenoid. You are looking for a stabbing or stuck VCt solenoid valve instigated by pollution. Mention to vehicle exact repair manual to achieve constituent tests for the VCT unit.