Would my 2023 Mitsubishi Challenger head gasket problem be covered by warranty?

Some Mitsubishi models in the past have had problems with a rough surface on the head-gasket sealing surface of the crankcase,. This has led to head gaket failures and coolant loss. This was fixed by about 2014 with a different machining process at the factory, so this could be your problem.

At the time, Mitsubishi issued a service bulletin for this problem and was modifying cars to fix them. However, whether this bulletin would still apply in 2025 is the big question. However, it would certainly be worth contacting Mitsubishi Australia’s customer service department to see if there’s still assistance available.