Just after I bought my used 2009 Murano from the dealer, the check engine light came on. They said there was a problem with the exhaust system. They replaced a canister and the light was reset. It then started coming on again and I was told it was the gas cap and that there wasn't a good seal and I should get a new one. I didn't and the light comes on all the time. Sometimes right after I get gas, the light will go off but it is almost always on.