A vehicle's engine coolant termperature sensor plays a significant role in preventing overheating. Here are four signs that it has failed and needs replacing.

A diagnostic test can tell if the temp sensor is working or not, but obviously cannot tell if it is giving the correct temperature readings. How could know that without an entirely separate coolant ...

Accuracy in cell testing can be affected by temperature, thus the need for temp-measurement sensors. And the positioning of that sensor is a sometimes overlooked, but essential, factor.

No, the engine is not overheating. As a matter of fact, it might take longer to reach normal operating temperature, and heater performance could also be affected.