TransmissionDiagnostic helpCommunity Starter

2018 Kia Optima — humming rises with road speed, not engine RPM

TruckPilot811Community StarterDec 14, 20252018 Kia Optima EXPhoenix

There is a low hum that rises with road speed regardless of engine RPM. Turning slightly left or right changes the sound. Is that enough to suspect a wheel bearing, or what else should I rule out? Mostly looking for the right next step.

2 replies

RoadMom737Community StarterCommunity StarterDec 15, 2025permalink

If it were in my driveway, two 2018 Kia Optimas can feel identical and have different causes, so measure before you copy someone else's repair. If the cheap test changes it, stop and reassess. Any freeze-frame data saved? Happens in gear, not in park, for what that's worth.

RoadMom737Community StarterCommunity StarterDec 15, 2025permalink

I'd want a measurement, not a hunch. A pressure test beats staring at a dry driveway if the 2018 Kia Optima is losing coolant with no puddle. Don't erase codes until someone who can help has seen them. This is from a 2018 Kia Optima in Phoenix. Have you gotten a second quote in writing? Cold start is when I can actually reproduce it.

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