I am the third owner, duh, of a 2010 Impala that has a foul odor out of exhaust. The local dealership replaced the cat but now 30 days later the smell is back. Should i buy a Honda? The car runs fine.

Rotten egg smell is usually caused by sulfur in the fuel, or a bad cat, or running rich. Sometimes you can smell this behind another vehicle that is trying to climb a big hill.

Go back to the dealer and ask them why it'* doing it again. You may end up paying a diagnostic fee, but be sure to pressure not having to pay.

Thanks Mike. I guess i am baffled why they would just replace the cat and not look for a cause. Only 30000 miles.

It'* still under warranty isn't it?

The cat is but thats it. Over 36 months. Might be a serious engine problem?

Unlikely, sometimes a bad fuel pressure regulator can cause your engine to run rich. But still, have the dealer check it out again.

Moving on to number 2 Mike. When i turn the car off when hot, i am getting a constant clicking sound from the exhaust area that lasts for about two minutes. I rent cars 5 times a month and i know you do get a clicking noise from that area. But this has the sound in the same two second intervals for the two minutes. It is not occasional. Any thing that could be "sticking" after i shut down like a solenoid?

Unless you could directly put a finger on it, then I would say its the exhaust cooling off. But then, their is a first for everything and might be a solenoid. I say bring it up with the dealer while you have your CAT in for warranty work.

Just got back from GM dealership. No codes. Maybe Obama can fix.

i would look at the evap solenoid, for the clicking, not likely the cause of the running rich though. that could be a number of things from air filter, maybe a failing o2, maybe fuel pressure regulator, maybe you have a bad plug or two.

you get gas at the same place all the time?