Buick's Grinding Gears Point to Failed Temp Sensor

Had similar trouble on a 2001 Buick LeSabre last summer. The symptoms matched exactly, transmission warning light, rough shifting, and grinding noises. Initially suspected the transmission oil temperature sensor, but diagnostic testing revealed the gearbox sensor was functioning correctly. The real problem turned out to be critically low transmission oil level due to a slow leak at the transmission pan gasket. The low fluid caused overheating problems and triggered the warning system. The transmission pan needed removal to replace the worn gasket and several worn seals were discovered during inspection. This was a serious issue that required immediate attention. Continuing to drive with low transmission fluid could have led to complete transmission failure. The repair involved draining and replacing the transmission oil, installing new gaskets and seals, and performing a transmission flush to remove any metal particles that had accumulated from the wear. After the repair, the transmission shifted smoothly again and all warning lights cleared. Regular transmission fluid level checks since then have shown no further leaks.

Thanks for sharing those details about your LeSabre transmission issues. The transmission oil leak situation sounds very similar to what I experienced. Quick question, do you remember roughly what you paid for the full repair? My mechanic just gave me a quote and I want to compare. Also, have you had any transmission issues pop up since the repair was done?

Since getting my car to the mechanic, they confirmed and fixed the faulty transmission oil temperature sensor. The repair also addressed the gearbox oil level, which was way too low. Total cost came to 365€ for parts and labor combined. Looking back at our similar transmission issues, the repair has proven completely effective. The transmission now shifts perfectly with no warning lights or unusual sounds. Regular checks over the past months have shown proper fluid levels and no leaks. This repair actually saved me from potentially more expensive transmission problems down the road. The diagnostic work revealed that catching transmission issues early, especially when related to oil sensors and fluid levels, tends to prevent major transmission repair bills later. My transmission has performed flawlessly since the fix, with no repeat problems or concerns.

Thanks everyone for the advice. I took my Rendezvous to a different mechanic this time. They found a failing transmission temperature sensor plus low fluid from a small leak. Total repair came to €420, they replaced the sensor, fixed the leak, and did a fluid change with new filter. The repair went smoothly and my transmission is working perfectly now. No more warning lights or rough shifting. The mechanic showed me the old sensor which was completely corroded. They also pointed out where the leak was coming from so I know what to watch for in the future. Really glad I caught this early before it turned into a major transmission overhaul. Regular checks of the transmission fluid level are now part of my maintenance routine. Three months since the repair and everything is still running great.