Check engine light came on......?

(2011-02-25 15:15:23) 1. Manuel M Says: last month i replaced the stock muffler with a glasspack it sounded deep and nice & then 10 days later the light came on.then i started hearing like rocks bouncing up and down in the catalytic converter when i turned off my truck.do you think thats why the light came on?2. dodge man Says: you can't hardly damage a cat when installing a muffler on one,you need to have a muffler shop check the back pressure on the cat and if its bad replace it,that's probably the inner part of it that's came loose and it will eventually wind up in the muffler and clog the exhaust system up on it,good luck with it.3. dodge man Says: your welcome, that's a good choice for a new cat,they give more flow through the exhaust than a stock one does,good luck. 4. cjo84070 Says: It could be. If they damaged the cat when installed it's possible. Go have the codes scanned and see why it's on. It could be anything. Without the codes it's tough to diagnose.5. Donnie Says: i think the person above me nailed it,i bought a truck that did that and the man knew it was like that,it was the catalytic converter on it,a 300 dollar repair at a muffler shop.6. The-Razors-Edge Says: Year, make, model of truck? Tag: Check engine light came on......?