Lexus SC transmission issue

I had a similar issue with my old Volvo C70. It wasn't exactly the same, but the symptoms sound familiar. The transmission would slip, especially when cold, and it threw a transmission warning light. In my case, it turned out that the oil level was indeed low. The automatic transmission is a complex system that relies on hydraulic pressure, which is related to the oil level. Reduced oil level leads to reduced pressure, which leads to the symptoms you describe. Have you checked the oil level and condition? The grinding noises indicate that the oil is not doing its job adequately anymore, potentially because it's low or contaminated.

Thanks for the insight. I did check the oil level, and it seemed within the acceptable range, although perhaps slightly on the lower side. How critical is the oil level in these transmissions? Could a small deficiency trigger such drastic symptoms? The grinding noise is what concerns me the most.

Yes, the oil level is critical. Even a small deviation from the optimal level can cause problems. The automatic transmission relies on very precise pressures to actuate the various clutches and bands. As for the grinding noise: It means there is metal on metal contact. This could be caused by insufficient lubrication or worn parts. In your case, the low oil level is the more likely reason. Considering the symptoms and the age of your Lexus, I would suggest taking it to a reputable workshop for a proper diagnosis and potential transmission service.

Thank you. Your feedback has been most helpful. I took it to a workshop, and the diagnostic confirmed the low oil level as the primary cause, exacerbated by a failing transmission oil temperature sensor. The repair, including a transmission service and sensor replacement, amounted to 365€. The transmission is now shifting smoothly, and the warning lights are gone.