Two problems related to engine exhaust system have been reported for the 2009 Nissan Altima. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2009 Nissan Altima based on all problems reported for the 2009 Altima.
2009 Altima 2. 5 sl. Consumer writes in regards to entering Nissan's consumer arbitration process the consumer stated the dealer had the vehicle on November 15, and 16, 2011 to inspect and repair a chronic mechanical issue that had been going on for the past 16 months. The vehicle would make a popping sound after the engine was warm, when the vehicle sat idle or turned off. While removing the initial heat shield rivets and replacing them with larger rivets, it resulted in a slightly muted popping noise. The consumer was concerned that overtime, the expansion and contraction of the metal surfaces will weaken and potentially fail. The dealer replaced the sepentine belt, tensioner and exhaust system, but the noise continued.
Popping noise from under car. Took it in and dealer first told me it was normal that it was the exhaust system cooling off. I did not accept his response because the popping was must too loud and I contacted Nissan America who got engineers involved. They finally concluded that it was the heat shield. The dealer worked on it and it seemingly got better for a while but it has kept recurring since then. I have taken it back to the dealer for rework several times and it helps for a while but returns. I have contacted Nissan american and they are currently getting engineering involved again. Hopefully they will come up with a fix. Very loud and annoying.