Does anyone know whats making a kind of humming / buzzing noise on an 04 cayenne at star up for couple of seconds and it goes away? This started happening recently and I am not sure if its something I should look into or it's normal. thanks.

 

coming from motor? dash? can you tell?

the secondary air injection pumps come on after startup for 30 seconds or so - I've not had one do this, but have read they can sound like a vacuum cleaner under the hood when they start going bad. I had one go bad in a 04 S but it didn't slowly fail, just died one day.

Make sure car is cool, open the hood, start up, and see if it is coming from the them...they are sitting on the right and left side visible above motor cover attached to firewall.

 

Thanks jpru2001 for your reply. I think it is coming closer from the dash. I noticed it also does it when the car is coming to a stop. Same buzzing noise for couple of seconds and goes away. I will check this method when the car is cool and see if it is from the air injections and keep you posted. It it is, do you know what it would cost to repair? Thanks.

 

there are two of them - I had a quote on mine for like 300 or 400 and that was for a pump replacement which is the most expensive repair. there are several hoses or valves that can go wrong that are next to nothing to repair.

I don't think that is it though if it sounds like dash. my '04 makes a ton of noises that come from the A/C solenoids which were a pretty documented issue.

 

I did this method to see it it is the air pumps. Opened the hood this morning started the car and waited to see it I will hear the noise from the pumps. Since I was able to locate them how you described it, was always wondering what those two things are. However I did not hear them make any noise at start up after waiting for it for about a minute. The car makes this noise on and off while stopped also. Not sure what it could be, will keep driving hope it will go away by itself or if becomes more frequent to take it for an inspection. Since there is another intermittent annoying noise I get when driving on uneven road from the suspension area feeling something rattling which needs more attention. Its an 04 Cayenne with 76k miles still premature I would say for struts job.

 

I was going to say maybe air suspension but you mentioned struts.

 

The model I have has the regular suspensions. It doesn't have the air kind where it has the option of lowering or raising the suspension. Except I am not sure what could be the reason its doing it to me. I took it to the dealer and test drove it with the technician and it makes no noise at all. Its ruining the drive when it does that and it is very hard to diagnose it. I had it looked at several places and everything looks ok but still making the noise intermittent when I drive it. Very annoying. Hoping it will fix itself or become more frequent to be diagnosed.

 

Hi all. I was checking back if anyone else had experienced this buzzing noise when coming to a stop. It sounds the loudest when the car comes to a stop and it is there until the car stars moving again. Not sure what it could be. Just replaced tow air flow sensors and it got worst, wasn't as loud before. The tech mentioned that it could be a spark plug issue. The spark plugs were replaced at about 40000 miles and now it has 82000. maybe it needs a major service (Spark plugs and air filters)?