* Transmission issues: This is the most serious possibility. Problems within the transmission itself, such as worn clutches, a failing torque converter, or low transmission fluid, can cause the car to hunt for gears, slipping in and out of overdrive. This often involves rough shifting or slipping.
* Throttle position sensor (TPS) or other sensor problems: The transmission relies on input from various sensors to determine the appropriate gear. A faulty TPS or other sensors (like the mass airflow sensor or oxygen sensor) providing incorrect data can lead to erratic shifting behavior.
* Transmission control module (TCM) problems: The TCM is the "brain" of the transmission. A malfunctioning TCM can cause incorrect shifting patterns, including hunting for overdrive.
* Low transmission fluid: Insufficient fluid can cause the transmission to overheat and slip, leading to erratic shifting. Check your transmission fluid level and condition. (Note: checking the level requires the engine to be running and the transmission at operating temperature).
* Transmission cooler problems: If the transmission cooler is clogged or malfunctioning, it can lead to overheating and shifting issues.
What to do:
If your Cavalier is shifting erratically, don't ignore it. Continuing to drive with a transmission problem can cause significant and costly damage. Here's what you should do:
1. Check the transmission fluid level and condition: Look for low levels or a burnt smell/dark color.
2. Have a mechanic diagnose the issue: A professional mechanic can properly diagnose the problem and determine the best course of action. They have the tools and expertise to check sensors, scan for trouble codes, and assess the transmission's health. Ignoring the problem could lead to a much more expensive repair later.
Ignoring the problem could lead to catastrophic transmission failure. It's best to get it checked out by a mechanic sooner rather than later.
