GMC Acadia Transmission Grinding & Limp Mode Issues

Had similar automatic transmission issues with my 2020 GMC Terrain last month. The symptoms matched exactly, rough gear shifting, grinding noises, and transmission warning lights. Initially thought it was just a transmission sensor malfunction. After inspection, it turned out the transmission fluid was critically low, causing overheating problems and sending the car into limp mode. The root cause was a slow leak from a damaged transmission line seal. The transmission repair involved: Replacing worn transmission line seals, Installing new transmission fluid sensor, Complete transmission fluid flush and refill, Computer system reset This was a serious issue that required immediate attention. Continuing to drive with low transmission fluid could have led to complete transmission failure. The damaged seals were causing fluid to leak slowly over time, and the sensor was actually working correctly by warning about the low fluid condition. Recommend getting a second opinion from another certified transmission specialist. These symptoms often indicate more than just a sensor issue, and proper diagnosis is crucial to prevent major transmission damage.

Appreciate your detailed response. Your experience sounds very similar to what I am experiencing with my Acadia. Great to hear you managed to fix those transmission issues before any major damage occurred. Question, would you mind sharing what the total repair cost was? Also, have you had any gear shifting problems or transmission warning lights since getting it fixed? I am especially concerned about the overheating problems you mentioned, as my car also feels warmer than usual when idling. Just trying to budget for potential repairs and would really value knowing what kind of costs I might be looking at.

Got my GMC Terrain back from the shop last week after dealing with those transmission concerns. Happy to report the gearbox sensor system is working perfectly now. The faulty transmission oil temperature sensor was indeed the main culprit, along with critically low gearbox oil levels. Total repair came to 365 Euro, which included parts and labor. Since the fix, gear shifting has been smooth with zero warning lights. The temperature readings are now stable and normal when idling. For reference, my transmission now operates at proper temperature levels and shifts effortlessly through all gears, exactly how it should. This repair was definitely worth every cent to prevent potential major transmission damage. If your symptoms match mine, strongly suggest getting it checked soon. Low transmission fluid combined with a malfunctioning temperature sensor can quickly lead to serious issues if left unaddressed.

Called my regular mechanic this morning and took the car in right away after reading these responses. Turns out you were all spot on, my Acadia had low transmission fluid due to a leaking seal, combined with a faulty transmission sensor. Total repair bill came to 410 Euro, which included: New transmission seals, Sensor replacement, Full transmission fluid change, System diagnostic and reset Mechanic finished the work in about 4 hours. Car shifts perfectly now, no more grinding sounds or warning lights. Temperature gauge shows normal readings and the automatic transmission feels smooth again. No more limp mode issues either. Glad I caught this before any serious transmission damage occurred. Having dealt with major transmission repairs before, this was actually a reasonable fix. Really appreciate everyone sharing their experiences, helped me push for a proper inspection rather than just accepting the initial simple sensor diagnosis.