In an automatic transmission, a sticking pressure relief valve may cause what issue?

In an automatic transmission, a sticking pressure relief valve can lead to a hard shift feel due to the inability of the valve to properly regulate hydraulic pressure within the system. When the pressure relief valve is functioning correctly, it helps maintain the right amount of hydraulic pressure necessary for smooth shifting between gears. If the valve sticks, it may either release too much pressure or not enough, resulting in abrupt or harsh shifting. This can create an uncomfortable driving experience, as the transitions between gears become less smooth and can feel jarring.

The issue of harsh shifts is critical because it can lead to additional wear and tear on the transmission components, making it essential for mechanics to diagnose and address the problem quickly. While the other options mention valid concerns about transmission performance and maintenance, they do not directly pertain to the specific symptoms caused by a sticking pressure relief valve as clearly as the hard shift feel does.