1. Low Transmission Fluid: Check the transmission fluid level and add more if it's low.
2. Faulty Solenoid: The solenoid that controls the shifting into 5th gear may be faulty.
3. Worn Synchros: The synchronizers in the transmission may be worn, preventing smooth shifting into higher gears.
4. Internal Transmission Damage: There may be internal damage to the transmission causing the shifting problem.
Additional Troubleshooting:
1. Try shifting into 5th gear at different speeds to see if the problem occurs at a specific speed or RPM.
2. Check for any fault codes stored in the vehicle's computer using an OBD-II scanner.
3. If you suspect internal transmission damage, you should have the transmission inspected and repaired by a qualified mechanic.
Possible Solutions:
1. Top Up Transmission Fluid: Add the recommended type of transmission fluid to bring it to the correct level.
2. Replace Faulty Solenoid: Replace the faulty solenoid responsible for 5th gear shifting.
3. Synchronizer Replacement: If the synchronizers are worn, they will need to be replaced to restore proper shifting.
4. Transmission Overhaul: If internal damage is found, the transmission may require an overhaul or rebuilding.
Note: Shifting into 5th gear at higher speeds may put additional stress on the transmission, so it's important to address the problem promptly to prevent further damage. If the issue persists or worsens, it's recommended to seek professional assistance from a qualified mechanic or a Mazda dealership for an accurate diagnosis and repair.
