Buick Transmission Warning: Bad Oil Pressure Sensor Fix

As someone with moderate experience working on cars, I dealt with a very similar issue on my 2004 Buick LeSabre. The symptoms you describe match exactly what I experienced, transmission warning light, emergency mode, and rough shifting. In my case, the transmission fault turned out to be related to critically low transmission fluid. The oil level sensor was giving incorrect readings, which led to the transmission running dry. The pressure switch was also affected due to insufficient fluid pressure. The repair involved: Complete transmission fluid level check, Replacing the transmission sensor, Replacing the oil pressure switch, Topping up with fresh transmission fluid Total cost was 365 for parts and labor. The repair completely resolved all symptoms and the transmission has been shifting smoothly since. Before suggesting specific solutions for your GL8, could you provide: Current mileage, When was the last transmission service performed, Are there any fluid leaks visible under the car, Does the problem occur more when the transmission is cold or hot, Any unusual transmission fluid color or smell This information would help determine if your issue matches what I experienced or if there might be other underlying problems.

Thanks for the helpful details. In my case at 45467 KM, I did notice that after replacing the transmission sensor and checking the oil pressure readings, the problem persisted. The transmission fault warning remained active even after a fluid level check and top-up. The grinding noise seems worse when cold starting. I was hoping the sensor replacement would fix it, but Im thinking it might be more serious based on the symptoms. Has anyone needed a full transmission rebuild to resolve similar issues?

Thanks for the update on your GL8 transmission issues. Having gone through this with my LeSabre, I can relate to your frustration when the sensor replacement didnt solve the problem. After my initial sensor replacement, I also faced persistent issues. In my case, the grinding noise during cold starts pointed to worn synchronizers. I ended up needing more extensive work than just the transmission sensor and pressure gauge readings suggested. My actual fix required: Transmission rebuild with new synchronizers, Replacement of worn clutch packs, Installation of updated pressure control solenoids, Fresh transmission fluid and filter The rebuild cost was significant but solved all issues completely. Based on your symptoms, especially the cold start grinding, its likely youre dealing with internal wear rather than just sensor problems. The transmission oil pressure might read normal, but internal wear can still cause shifting problems that sensors wont detect. Given the similar age of our vehicles, internal wear is a common issue at this point. Have you noticed any metal particles in the transmission fluid? This could confirm internal wear and help decide if a rebuild is necessary.

Thank you for sharing that experience. After getting those grinding noises at cold start and dealing with the persistent transmission fault warning, I finally got it properly diagnosed. The mechanics found metal shavings in the transmission fluid after doing a pan drop inspection, confirming significant internal wear. The oil pressure sensor and transmission sensor replacements clearly werent enough to fix the underlying problem. Given the metal contamination and continuing issues even after addressing the sensor fault, Im going ahead with the full transmission rebuild rather than risking more damage. Going to have them replace all the worn synchronizers, clutch packs, and solenoids while theyre in there. Not the news I was hoping for when this started, but at least I now know what needs to be done to properly resolve these transmission problems rather than just chasing sensor issues. The grinding noise during cold starts should have been a bigger red flag from the beginning.