P410 help!
Please excuse my English. My 2011 c63 just threw p410 code every 2-3days. Work shop did smoke test but can't find anything so they took the manifold off and said the exhaust check valve is stuck open. Head need to come off for proper clean and warranty won't cover as I bought it used. Is it common issue on this engine?. Some said it's need a good hard driving every now and then to keep the engine hot enough to burn the gunk out( my wife use this car to take kid to school and back) .
any advise will be appreciated








