* Low Transmission Fluid: Check the transmission fluid level *immediately*. Low fluid can cause significant damage, and even a small leak can lead to this type of failure. However, low fluid is unlikely to only allow first and reverse.
* Transmission Linkage/Shift Cables: While less likely to cause *only* first and reverse to work, a problem with the linkage or shift cables could prevent the transmission from selecting the other gears. Inspect the linkage for damage, binding, or disconnections.
* Internal Transmission Problems: This is the most probable cause. The problem almost certainly lies within the transmission itself, possibly including:
* Broken or worn clutch packs: These are responsible for engaging each gear. Failure of the clutch packs for second and third gear is the leading suspect.
* Worn or damaged planetary gears: These are internal components that allow the transmission to change gear ratios. Damage to these gears is a major issue.
* Problems with the valve body: The valve body controls the hydraulic pressure that engages the clutch packs and planetary gears. A faulty valve body can prevent gears from engaging.
* Low or contaminated transmission fluid: While checking the level is crucial, the *condition* of the fluid is equally important. Burnt, dark, or smelly fluid indicates internal wear and damage.
What to do:
1. Check the transmission fluid level and condition: This is the first and most important step. If it's low or contaminated, you'll likely need a transmission fluid and filter change at a minimum, but further damage is probable.
2. Inspect the transmission linkage and shift cables: Look for any signs of damage, wear, or misalignment.
3. Professional Diagnosis: Given the symptoms, you almost certainly need a professional transmission mechanic to diagnose the problem. Attempting repairs yourself without the proper tools and knowledge can lead to more extensive damage and higher repair costs. The mechanic will need to inspect the transmission internally to pinpoint the exact cause.
Repair Costs: Repairing a transmission can be expensive, ranging from a few hundred dollars for a simple fix (like a linkage problem) to thousands of dollars for internal repairs or a complete rebuild/replacement. The age and condition of the transmission will heavily influence the cost. Consider the car's overall value before investing significantly in repairs. It might be more economical to replace the vehicle depending on the cost estimate.
