Car had been making loud gritty noise. Took car into fontana Nissan for diagnosis. Was told it was a cracked and leaking exhaust manifold. It was at no cost to us due to warranty and they replaced it. This was in August 2012. Noticed the same noise again in November 2012 and decided to take it in to fontana Nissan. The mechanic told me that they have to repair the exhaust manifold due to cracking and leaking. I advised it was recently replaced and they just said it needed to be replaced again. In May 2012 the car started making noise again. Took car to fontana Nissan and they found that the exhaust manifold was cracked and leaking! after the part being replaced, not just repaired, but replaced twice! the mechanic suggested we contact Nissan usa first to file a lemon or submit application for buy back. It took roughly 3-4 weeks for them to review case. In the meantime we have found other exhaust manifold problems in earlier models, found out that carbon monoxide is the gas that leaks from the exhaust manifold and is seeping onto the cabin of my car. Symptoms of low dose carbon monoxide poisoning is sleepiness among other symptoms. I am constantly sleepy in that car and have to talk to someone on the phone most of the time just to get to my destination. I do not have that problem in our truck! received all on Wednesday from Nissan and they have denied our claim. Will not tell us why! I am 7 months pregnant with a 3 year old asthmatic child that is constantly in the car. I am attempting to appeal decision but need help. Since the review process car has still had crack and leak. Nissan is not helping. Reaching out to gather research as to what can be done. What would cause 3 exhaust manifolds to do this in less than a year" what if I fell asleep at the wheel and got in a serious accident? what if my 3 year old or unborn child is affected"

- Beaumont, CA, USA

Mildew in air condition. Terrible smell coming from vents. Burns your eyes and gives terrible migraines. Changed 3 cabin air filters and used multiple cans of mildew removal. Please help. Any recommendations?

- Mechanicsville , MD, USA

Went to start vehicle and it did not start. Had to have it towed to dealership for $90. Was told it was not covered under warrenty and my car was out of warranty by 2 months. Advised to call Consumer Affairs. Waited 13 days with repeated phone calls just to be told they will not warranty the repair with no written explanation. Repair cost $757 and is only warranteed for 12,000 miles. Was told repair would take 3 days but they had my car for 21 days because the part was on back order. By the way, my car was also in for 2 recall issues: Head gasket and master brake cylindar. Pretty big issues! I was also told by service manager that if I had all my service done thru them instead of outside source they would have covered the steering lock issue. Sounds a little fishy to me. They need to recall this problem!!! or at least have a manual over ride.

- Canyon Lake, CA, USA

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.

- Andover, MN, USA

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.

- Macon, GA, USA

This is extremely urgent and important! I have a 2009 Nissan Altima. The other evening, I parked inside the lower level garage of my condominium. It is quite noisy. I have the keyless feature. I parked, pulled the starter instrument from its holder, got out of my car, hit lock on my instrument. And went to my unit. The engine was still running, and ran all night until the next day. There should be some safety feature, a warning device, or automatic shutoff upon exiting the car. There is nothing. Someone eventually going to leave this model car running in their home because of this and someone is going to die. Please act on this immediately!

- Miami Beach, FL, USA