Is this normal? I always hear this hissing noise underneath the rear of my bumper somewhere by the muffler while the car is parked, engine off.
This usually happens approximately 5 hours after I have parked in the garage where it is quiet.
The hissing sound lasts about a minute then shuts off.
Is there something electrical there by the muffler? Some kind of gas evaporator or something? I went underneath and can't pin point where the sound is coming from.
Ok, the sound is more like a small air compressor motor sound than hissing but not as loud.