[deven11]

Right after starting the car (engine off and fan is off too), I heard a short but fast knocking sound almost like someone was knocking on a door. There were maybe 4-5 knocks and they disappeared. I could not tell where they came from. Has anyone heard the same? I know hybrid system makes a lot of noises but I am not sure if this is normal. Thank you.

 

[70mach1owner]

I've had my '21 just over 2 years and I can say I have never heard that type of sound. Only sound close to a knocking comes from the direct injection fuel pump. But the engine must be running. And this pumps knocking sound is muffled. Could this knocking sound coincide with you putting it in gear which releases the parking brake at same time?

 

[deven11]

It turns out that every time I open the fuel cap door and close it, the knocking noise will appear for 15-20 seconds, much longer than it is on startup. I could hear it both inside and outside the car. I wonder if the fuel canister or valve is malfunctioning.

 

[70mach1owner]

It turns out that every time I open the fuel cap door and close it, the knocking noise will appear for 15-20 seconds, much longer than it is on startup. I could hear it both inside and outside the car. I wonder if the fuel canister or valve is malfunctioning.

I know there is an evacuation pump for the fuel system that pumps vapors from the system into charcoal canister (old days) probably called something else today. And while I know it makes a slight noise, its nothing like the loudest and length of time you are talking about. Hate to say it but if you can recreate the sound, I'd suggest a trip to the dealer.

 

[Rambocat]

I know this is a little off the main topic here but thought I would ask anyway since we are discussing strange sounds. Each time I come to a full or almost full stop I hear what sounds like an emergency vehicle siren. It always goes from high pitch to low pitch. Have had the car a few short months and have not brought it up with dealer. Have gone through all or most of the topics discussed on this car and have seen nothing mentioned on this sound. Thought I could get used to it but it still bothers me unless I have the audio on. By the way, it is different from the built-in EV artificial warning sounds.