Rattling Hyundai
Some Hyundai Elantra vehicles may experience a rattle noise from the front muffler with the brake applied in Reverse after a cold start. The noise does not occur after engine warm-up. This applies to 2011 Elantras equipped with an automatic transmission, in production range 11-12-2010 through 12-30-2011.
Raise the vehicle on a hoist. Apply the parking brake and start the engine. Place the shift lever in the Reverse position. Check to see if the noise is coming from the front exhaust muffler.
Use a screwdriver to press against either of the two locations shown in Figures 1 and 2. If the noise is reduced or stops, replace the front muffler.
PARTS INFORMATION
Front muffler assembly     28610-3X300                FED 11
                                        28610-3X400                CAL 11
 Exhaust gasket              28751-2V000                FED 11/CAL 11
                                      28751-3X000                FED 11/CAL 11