Anyone familiar with this p1456 code for evaporative fuel system leak? I understand it is typically a lose gas cap, but in my case apparently not. I have tightened the cap and code has not cleared itself after several days.

Any thoughts on which particular components of the system to check next? Is there a part that frequently fails? How about the caps themselves?

Thanks.

 

bad 2 way bypass valve.

 

reset the light (disconnect battery cable) first just to verify that the gas cap didnt fix the prob, then go with the 2way bypass thing.