Final answer:
A thermostat stuck open can cause a sudden decrease in engine operating temperature, affecting performance and fuel efficiency.
Explanation:
A thermostat stuck open would be the most likely cause for the engine operating temperature suddenly reading lower than usual. When the thermostat is stuck open, it allows coolant to flow through the engine constantly, which prevents the engine from reaching its optimal operating temperature.
This malfunction leads to inefficient fuel combustion, increased wear on engine components, and decreased overall performance. If the engine temperature remains low, it may lead to poor fuel economy and increased emissions.
Learn more about Engine Operating Temperature here:
https://brainly.com/question/43351185
