I have a whistling sound under my hood when I accelerate....

I have a whistling sound under my hood when I accelerate. I plugged in a code reader I got 2 codes, code P0420 and P0340 Mechanic's Assistant: How old is the transmission? Have you checked the fuel filters? I have not che...

I have a whistling sound under my hood when I accelerate. I plugged in a code reader I got 2 codes, code P0420 and P0340 Mechanic's Assistant: How old is the transmission? Have you checked the fuel filters? I have not checked the fuel filters. Mechanic's Assistant: What is the make/model/year of your car? 2005 Nissan Altima 2.5 engine Mechanic's Assistant: Are you fixing your Altima yourself? What have you tried so far? I am going to try to fix it, really on thing I’ve tried is looked for a disconnected air valve or see if an air valve is cracked. I don’t know where else to check. Everything I’ve looked up leads to and air leak or the catalytic converter Mechanic's Assistant: Anything else you want the Mechanic to know before I connect you? Only that the is a whistling sound and it’s takes a little longer to accelerate when driving

Automotive Expert
Hi, my name is\*\*\*\*\*’ve been a technician on Just Answer since 2007 and I'll be helping you today. I'm sorry to hear you are having difficulties with your vehicle. I know how inconvenient car trouble is, but together, we will get your vehicle back up and running quickly. May I ask whom I am chatting with today?

No thanks. Messaging is best for me right now
Automotive Expert
Hi Daniel it's nice to meet you. It sounds like the catalytic converter might be plugging up. This will force the exhaust back through the pipe and maybe cause a leak or the whistling you are hearing. You may want to drop the front pipe and take a peak at the substraite in the converter to see if it's broken or not. As for the cam sensor code, you probably just need to replace the cam sensor to solve that one, but the converter with a whistle is the bigger of the two problems at the moment. Check it and let me know.

If it needs replaced would I just have to replace the catalytic converter under the hood or the one under neither the vehicle also?Underneath\*\*\*
Automotive Expert
If it's broken up, then you will have to take the front pipe off and clear it out.Not remove the converter but dump the front pipe, otherwise just the main one off the exhaust manifold. That's the only one that is monitored

Ok. Could a bad catalytic converter cause an exhaust smell in the cab of my vehicle also? or is that something else?
Automotive Expert
If it's forcing the exhaust back up out of the gasket then yes, you would smell that in the car.

Ok. Would It be better to just replace the piping under the hood? If I do would that fix my issues about the whistling and the poor acceleration when I drive?
Automotive Expert
I can't give an honest answer without being there, but based on what you have told me, I think you are going to need a new converter and to check the exhaust pipe. Replacing it may be the answer, hard to know without actually seeing it.

Ok. I will take it off and check it and see if it’s clogged and just replace the catalytic converter under my hood.
Automotive Expert
I think it's the best place to start.

Alright. That helps! Thanks a lot!
Automotive Expert
You're very welcome.

Have a happy new year!
Automotive Expert
Thanks and to you as well!

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