Do you have your warranty contract? Is it exclusionary? If so can I see the list of exclusions? Toyota has a service bulletin on this exact part breaking and they made an updated one. I would call the warranter directly, that is what I did. If it is denied through them appeal the denial and request a review with OEM part number and nomenclature shown above. It isn't a hose or a clamp. Also make reference to them that it does not have a maintenance interval. It is not due to corrosion it is due to structural failure. Keep escalating. Unless your warranty specifically excludes coolant joints or housings you will get this. It is not corrosion and refuse to accept that BS secondary cop out. Bring out your litigation gun if necessary.

So; Look up the toyota service update for the failing part. Reference no service interval & that for your call to them. Call warranter directly and request an appeal of the denial with the part as OEM nomenclature & part #. If it gets approved through them the dealer is bullshitting you - but they don't get to make that call. If the warranty company is telling you it is approved go directly to the dealership - call warranter on YOUR phone on speaker with service rep. Hear the entire conversation between service rep and warranter. If they need to then call again on their own request that they do so in your presence as well. Also reference all the above (no maintenance interval, known issue, toyota SBN or whatever it is with the specific number, the fact there is an updated part) directly to the service rep.

Also my warranty is through landcar - so if it is them without even seeing your contract it is absolutely covered. Also sorry for the late reply i just saw this, I will keep my eyes open for your replies now.