What actions should be taken if engine temperature readings are excessively high during flight?

In the event of excessively high engine temperature readings during flight, the most appropriate action is to perform a controlled descent and troubleshoot the situation. High engine temperatures can indicate potential issues that need to be addressed promptly to prevent engine damage. By descending, you're allowing the aircraft to cool down, reducing stress on the engine while also maintaining control over the aircraft's performance.

This controlled descent provides an opportunity to troubleshoot and assess the situation. Pilots can verify the readings, check the engine instruments for other indications of trouble, and consider whether any corrective actions can be taken, such as adjusting the mixture or maintaining a suitable airspeed to improve airflow over the engine.

The other choices would not effectively manage the high temperature. For example, increasing the throttle to maximum could exacerbate the overheating. Opening all cabin doors would not help with engine cooling and could create a dangerous situation. Reducing altitude without changing the power setting may not provide sufficient cooling without addressing the underlying issue causing the high temperature. Therefore, the most logical and effective response is to perform a controlled descent while troubleshooting the problem.