My 1995 mazda protoge lx 1.5l auto.transmission will not to shift into over drive. What could cause this?

There are several potential reasons why your 1995 Mazda Protege LX with a 1.5L engine may not be shifting into overdrive. Common causes include low Transmission Fluid levels, a faulty transmission control module, or issues with the throttle position sensor. Additionally, problems with the transmission itself, such as worn clutches or internal damage, could also prevent it from shifting into overdrive. It’s best to have a professional mechanic diagnose the issue for a proper solution.