Seems to seal good. The printed instructions on the cap are Wrong. You must turn the key 1/4 turn clockwise, leave the key in, turn the cap counter clockwise to remove. Remove key then screw cap on clockwise until 3 clicks. This needs to be fixed, because it makes it very confusing and frustrating since it does not come with additional instructions. When installing the cap it cross threads easily and can get stuck on the fill neck, so take your time installing. It is new, so I cannot comment on long term. So far, no check engine light. The keys are solid metal which is nice. I wish it came with a tether like the original. A locking cap is a must these days and all Toyotas should have a locking fuel door like most other vehicles.
Thank you for the detailed feedback. We're glad the cap seals well and that you're off to a good start with it. You're absolutely right about the instructions—thanks for pointing that out. We’ll make sure to correct them.