* Low Transmission Fluid: This is the first and easiest thing to check. Low fluid leads to insufficient lubrication and pressure, causing the transmission to slip and not shift properly. Check the fluid level with the engine running and warmed up, using the dipstick (if equipped). Low fluid could indicate a leak somewhere in the system, which needs immediate attention. Do not add fluid if it's low without first identifying the leak. Adding fluid to a transmission with a major leak can cause it to burst.
* Faulty Transmission Fluid: Even if the level is correct, old, contaminated, or incorrect transmission fluid can cause shifting problems. The fluid degrades over time, losing its lubricating and hydraulic properties.
* Internal Transmission Problems: This is the most serious and expensive possibility. It could include:
* Worn Clutch Packs: These are responsible for engaging and disengaging the gears. Wear and tear lead to slippage and inability to shift properly.
* Broken or Worn Internal Components: Various internal parts like gears, bands, or valve bodies can fail, leading to shifting issues.
* Solenoid Problems (Automatic Transmission): These electrically controlled valves regulate fluid pressure to shift gears. A faulty solenoid can prevent proper shifting.
* Valve Body Problems (Automatic Transmission): The valve body controls fluid flow within the transmission. Internal problems here can cause a wide range of shifting issues.
* Torque Converter Issues (Automatic Transmission): A malfunctioning torque converter can prevent smooth power transfer and shifting.
* Shift Linkage Problems (Manual Transmission): If it's a manual transmission, a problem with the linkage (cables or rods connecting the shifter to the transmission) could prevent the gears from engaging correctly.
* Computer/Sensor Issues (Automatic Transmission): The transmission control module (TCM) and various sensors monitor transmission operation. A faulty sensor or TCM can send incorrect signals, resulting in poor shifting.
What to do:
1. Check the transmission fluid level and condition immediately. This is the easiest and cheapest thing to check first. If it's low, find the leak before adding any fluid.
2. If the fluid is low or dirty, get it changed (along with the filter if applicable) by a qualified mechanic. This may solve the problem if it's caused by simply old or contaminated fluid. Never attempt a transmission fluid change yourself unless you are very mechanically inclined and familiar with the proper procedure.
3. If the fluid level and condition are okay, you need to take the car to a qualified transmission specialist or mechanic. They have the diagnostic tools and expertise to determine the specific cause of the problem. Driving the car while it's redlining will cause catastrophic damage to the transmission and possibly the engine.
Ignoring this problem will likely lead to a complete transmission failure, resulting in a very costly repair or replacement. Get it checked out as soon as possible.
