Lexus GS transmission issues

Hey there! I have a GS too, and I had a similar problem a while back. Implausible shifting behavior, transmission light – sounds familiar. Did you notice any changes in fuel economy, or hear any unusual noises coming from the gearbox before this started? Have you checked the transmission fluid level and condition? A low fluid level or contaminated fluid can definitely cause these issues.

Thanks for the quick reply! Fuel economy seems normal, and I haven't noticed any strange noises. To be honest, I haven't checked the transmission fluid myself. Is it easy to do, and is there anything specific I should look for besides the level?

While you can check the fluid yourself, you'll want to make sure you know where to look and that the engine is warm. You're looking for the fluid to be a healthy red color, not brown or black, and not burnt. With all those symptoms, it really does sound like you might want to go to a workshop and have it checked out by a professional. It could save you from further damage down the line. Likely you would need a full transmission flush including a new filter, with new transmission fluid. And that might fix the issue or improve transmission performance greatly.

Thanks a lot for the advice! I took it to a workshop, and you were right – the transmission oil was worn out and undervoltage made it even worse. They replaced it, did a transmission flush, and now it's shifting smoothly again. The total repair cost was around 240€ Appreciate the help!