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2001 Toyota Avalon Humming Coming From Rear?

Hello, I am trying to figure out what this humming could be coming from. The humming is a medium to medium/high pitch sound that is definitely noticeable inside and outside of the car. It occurs at an RPM level around 1600-1800. The noise will stop as soon as I let off the gas. It does it in neutral and with the transmission engaged (so I do not think it is the transmission). It occurs in the back of the car and is equal in loudness between the right and left rear tires (maybe a little louder on the left side). I took it to discount auto and put it on the meter and it gives me codes of P0441 and P0446 (which deal with the emissions). I bought a repair manual for the car and I was going to start checking all the emission parts that I could test. However, most of the parts are in the engine and not near the rear of the car. Does anyone know what this could be? Thanks for checking out the post Craig Is there anyway to check if there is an obstruction in the exhaust? In regards to the fuel pump. I am just curious if it is the fuel pump would there be a decrease in performance when the noise occurs?

Public Comments

1. Seems to me it's likely to be a part of the exhaust system touching the chassis of the car somewhere. Lots of the cars now have rubber suspension parts on the exhaust pipes and if one lets go, the thing gets out of line and clunks, clanks and makes other noises. Also the emissions codes would have nothing to do with noises, only engine performance that contributes to mileage and emissions.
2. Is the noise coming from the exhaust? If it is I would suspect an obstruction in the exhaust causing the codes and making the wierd sounds.
3. it could be that you have a hole in the exhaust.Or in the catalic converter which deals with emissions.
4. its either u-jints or the rear end differentual
5. These two codes are related to small and large evap leaks in the fuel system. Doesn't mean it leaks fuel but it allows the gas vapors to be eliminated in the atmosphere. Most likely these codes are caused by the canister close valve. This valve, even defective would not cause this kind of humming sound. This looks like is your fuel pump. Has gotten to a level where it starts acting up before goes down indefinitely. Have this checked by a technician (not a back yard guy). Good luck Not really. The fuel pump does not affect performance. It starts with noise and finally gives way. Brakes down and won't start the engine. Lost performance could be related to ignition rather than fuel delivery. The only time you loose performance due to fuel system is when fuel filter is clogged.