What symptom may indicate a transmission fluid leak?

A puddle of red fluid under the vehicle is a classic indicator of a transmission fluid leak. Transmission fluid is typically bright red or pink, and finding this color fluid underneath the vehicle is a strong sign that the transmission system has a leak. This visible pooling can occur when there is a failure in the transmission case, seals, or gaskets, allowing the fluid to escape.

While a fluid odor can suggest overheating or breakdown of hydraulic fluid, it does not specifically indicate a leak. Similarly, slipping during gear changes and unusual noises when shifting might indicate transmission issues but are not direct signs of a fluid leak. Instead, these symptoms may point to other mechanical problems within the transmission itself. Therefore, observing puddles of red fluid is the most direct and obvious symptom of a transmission fluid leak.