Lexus UX Bypass Valve Error Overheating

I drive a Lexus UX as well. I've experienced something analogous: think of it like a domino effect. A minor coolant leak can lead to low coolant levels, which then stresses the entire cooling system, potentially triggering the bypass valve error and causing overheating. I would first look at the coolant level.

Thank you for your swift response. Could you elaborate on which specific areas I should inspect for potential coolant leaks, and whether a compromised vacuum system could also contribute to this cascade of errors?

Focus your attention on the usual suspects: radiator hoses, the water pump area, and the reservoir itself. Look for any signs of residue or dampness. As for the vacuum system, it's less directly related, but a significant leak there could impact fuel efficiency and potentially contribute to engine stalling, indirectly exacerbating the overheating issue. However, given the error code and overheating, I'd strongly advise a visit to a qualified workshop for a thorough diagnosis. My issue ended up requiring professional tools to identify the leak source.

I appreciate the detailed guidance and analogy. Following your advice, I had the vehicle inspected by a workshop. It turns out the bypass valve error was indeed a consequential error caused by a faulty sensor, which was replaced under warranty. The repair cost was 0€.