alfredstern5
Volvo S90 Torque Converter Failure
Summary of the thread
A 2020 Volvo S90 hybrid is experiencing issues with the check engine and transmission indicator lights on, along with symptoms of slipping and grinding noises during gear shifts. The problem is suspected to be a defective torque converter lock-up clutch, which can cause drivability issues if it fails. The humming noise previously heard at highway speeds likely indicated the beginning of the clutch failure. The recommended solution is to have the torque converter replaced by a specialist, as it requires professional equipment and expertise.
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4 comment(s)
alfredstern5 (community.author)
Thanks for the quick reply! The transmission fluid was supposedly changed at the dealership during the 120,000 km service, so about 40,000 km ago. As for noises before the light, now that you mention it, there was a kind of subtle humming sound at highway speeds for a while. I thought it was just road noise, but maybe it was related? Is there anything I can check myself, or am I looking at a workshop job?
adriankoehler1
That humming noise is a strong indicator, and the mileage since the fluid change means that's likely not the issue. Given the symptoms and error codes, a defective torque converter is almost certain. The humming was likely the clutch starting to fail. Replacement is probably the only solution. While there are theoretical tests, they require specialized equipment. This is really a workshop job, I advise to seek out quotes for a transmission repair.
alfredstern5 (community.author)
Okay, I appreciate the confirmation. I was hoping it was something simple, but it sounds like I need to bite the bullet and get it to a specialist. Turns out you were spot on. Got it diagnosed, and it's a defective torque converter. Repair cost is going to be around 2120€. Thanks for the help in figuring this out.
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VOLVO
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S90
adriankoehler1
Converter fault is certainly a strong possibility given your symptoms. Slipping, grinding, and error codes all point in that direction. The lock-up clutch inside the torque converter is designed to create a direct mechanical connection between the engine and transmission at certain speeds to improve fuel efficiency. If it fails, it can cause all sorts of driveability problems. When was the transmission fluid last changed? And have you noticed any unusual noises before the check engine light came on?