tonyczhang

I just bought a new ES 300H 2019 two days ago. I found there is a very annoying hissing sound come and go when I try to stop, reduce the speed or reverse, especially at low speed. I am sure it is not the hybrids proximity notification sound. I doubt this is regenerative braking sound but it is too loud.

This is my first Lexus hybrid car. Just wondering if you all have the same sound for your ES 300H 2019?

The attachment is the mp3 audio clip I just record. It happened in the first 2 seconds. It is not very clear on the audio file but actually very loud when I am driving.

Please volume up to hear the noise in the first 2 seconds. If this is not normal, I may need to check with the dealer.

Thanks.

E46CT

That sounds like your brake booster. That's normal. Every car does that. It's just hybrids are silent when the engine is off.

The brakes require a lot of force to hydraulically actuate them, it's not magic. So the brake booster is charged and the hissing is just pressure bleeding out as unused pressure bleeds out. Then it gets recharged again and the cycle repeats itself. Completely normal.

TechNut

We are currently on our third Lexus hybrid and this noise is not familiar to me - although I am having some difficulty hearing exactly what you are referring to. I would recommend you take it to the dealer and let them listen. Better safe than sorry in my opinion. Hybrids will make a little bit of a whine from time to time, and there is the sound from that darn noise maker they are now putting on new cars, but I can't recall any other strange noises. We also typically drive with our windows up so if there is any other noise from outside the cars we probably wouldn't hear it. Again, it can't hurt to let the dealer evaluate this, aside from your time. Hopefully your nearest dealer isn't too far away.

tonyczhang

Just check with dealer service department and the sales person. They hear the sound and all conclude the sound is normal. It is from the brake generate electric power back to the battery.

User 41924

We've had 2 Lexus Hybrids, and I've never heard a hissing sound. That would alarm me! There is a whine from the regenerative braking when slowing. I normally hear it at slower speeds and the pitch changes as you continue slow, clearly. You should also see the Hybrid System Meter on your dash in the "Charge" section whenever you hear the sound.To me it clear that it's an electric motor type of whine sound, though. Not a hiss. If that's what you're hearing it's OK. I kinda like that sound in our RX.

tonyczhang

Thanks everyone who reply this post. Now I am sure the sound I hear is normal. Today, I meet the sales person, a Lexus dealer technician and another ES300h 2019 car owner, they all hear the sound and believe it is normal.