My Hyundai Elantra 2008 GLS with 13,800 miles on it had a vibrating rattle especially when idling but also while driving although not always. I bought the car used. After four months of going crazy with the sound we found that it was coming from where the back seat joins the frame. It is not tightly joined there nor is it cushioned. We stuffed some thin cardboard around it to tighten it. That keeps it from vibrating and rattling.
I had this problem, I had a faulty TPS sensor
The computer has detected a problem with the emissions system. Take it to a professional.
The first thing to check is the gas cap to see if it is on tight and the gasket is in good condition. After that, it gets tricky.
no oil
The rattling you are asking about turned out on my 320 to be the catalytic converter breaking up internally.
You need check the transmission module first(very popular problem with 01-03 elantras), connectors(outside on the transmision) ,scan your computer to get some codes. po713 po760 po745
Is your oil level?
Check your gas cap. Lots of times its not on tight and causes your light to come on. After you check your cap remove your negative battery cable for a minute to clear the computer and then see what happens
The guy in the trunk is still alive!!!
Possibly a loose heat shield or other component.
Two main causes: the inner parts have failed, or the outer heat shield has failed.
What causes a hard rattling knocking sound under the hood when you start your 98 ford windstar? Lack of oil, lack of oil pressure, badly worn camshaft or crankshaft or a combination of all the above.