* Clutch Issues (Manual Transmission): The clutch might not be fully disengaging, preventing the transmission from shifting properly. This could be due to a worn-out clutch plate, pressure plate, or throw-out bearing. A sticking or broken clutch cable or hydraulic system is also possible.
* Transmission Problems (Manual Transmission): Internal problems within the transmission itself are a strong possibility. This could include:
* Broken or worn synchronizers: Synchronizers are responsible for matching the speeds of the gears before engagement. Worn or damaged synchronizers will make shifting into higher gears difficult or impossible.
* Damaged gear teeth: Broken or severely worn gear teeth will prevent the engagement of higher gears.
* Shift forks or linkage problems: These components move the gears within the transmission. Problems here will prevent proper shifting.
* Low transmission fluid: Insufficient fluid will lead to friction and difficulty shifting.
* Transmission Problems (Automatic Transmission): With an automatic transmission, the culprit could be:
* Low or contaminated transmission fluid: This significantly impacts the hydraulic system that controls gear selection.
* Problems with the valve body: The valve body controls the flow of transmission fluid, and a malfunction can prevent shifting.
* Solenoid issues: Solenoids are electromagnets that control the valve body. A faulty solenoid can stop the car from shifting.
* Torque converter problems: The torque converter transfers power from the engine to the transmission. A malfunctioning converter can cause shifting problems.
* Internal transmission failure: Similar to manual transmissions, significant internal damage could prevent proper gear shifting.
* Shift Linkage/Cable Issues (Manual Transmission): Worn or damaged shift linkage or cable can prevent the gear selector from properly engaging the gears in the transmission.
* Engine Problems (Less Likely): While less likely to be the *sole* cause of this specific symptom, engine issues *could* indirectly contribute if the engine is struggling to produce enough power to overcome the resistance created by a problem elsewhere in the drivetrain (though it'd likely manifest as problems beyond just higher gears).
What to do: You need a professional mechanic to diagnose the issue. Trying to troubleshoot this yourself, especially with an automatic transmission, is strongly discouraged as you risk further damage. Describe the problem clearly to the mechanic, emphasizing that you can only accelerate in first gear. They will be able to pinpoint the cause and recommend the necessary repairs.
