1AEEM00620-2002-06 Nissan Altima Sentra Exhaust Manifold Catalytic Converter Assembly



2003 Nissan Altima L4 2.5L Exhaust Manifold Catalytic Converter Assembly

Guaranteed to fit 2003 Nissan Altima

02-06 Nissan Altima Sentra 2.5L Exhaust Manifold w/Catalytic Convertor
$ 199.95
29% OFF
29% OFF
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Part 1AEEM00620

Orders must be placed by 2pm ET
Part 1AEEM00620
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Estimated Arrival Cost

Deliveries made to PO Boxes and FPO may take longer. See our Shipping & Delivery for more information.


Vehicle Fit

Warranty & Shipping
How-To & Tools

Install Tip: You may be required to reset the vehicle computer after installation of this part.

Item Condition: New

Lifetime Warranty

This item is backed by our limited lifetime warranty. In the event this item should fail due to manufacturing defects during intended use, we will replace the part free of charge. This warranty covers the cost of the part only.

Emissions Note - Due to state emissions regulations:

  • We cannot ship this item to California or Colorado, as it is not California Air Research Board approved.
  • In the state of New York, this item cannot be installed on California emissions equipped vehicles.
  • In the state of Maine, this item cannot be sold for or installed on a 2001 model year or newer, California emissions equipped vehicle.
  • Emissions information can be found on a tag under the hood or from a dealership based on your VIN.

How to Replace Exhaust Manifold Assembly 02-06 Nissan Altima

Created on: 2013-11-18

Watch this video to learn how to fix a broken, leaking, or loud exhaust. The experts at 1A Auto show you how to replace the exhaust manifold and catalytic converter in your 02-06 Nissan Altima.

  1. step 1 : Disconnecting the Battery
    • Disconnect the negative battery cable with a 10mm socket and ratchet
  2. step 2 : Removing the Oxygen Sensors
    • Disconnect the downstream O2 sensor wiring harness
    • Remove the downstream O2 sensor with an O2 sensor socket
    • If the O2 sensor socket does not work, cut the wires off the O2 sensor
    • Then remove the O2 sensor with a 7/8 inch socket
    • Disconnect the upstream O2 sensor wiring harness
    • Remove the upstream O2 sensor with an O2 sensor socket
  3. step 3 : Removing the Alternator
    • Apply penetrating oil to the four bolts on the catalytic converter heat shield
    • Let the penetrating oil sit
    • Remove the 4 5mm Allen bolts from the engine cover
    • Remove the engine cover
    • Remove the two 10mm bolts from the alternator
    • Disconnect the alternator wiring harness
    • Remove the 12mm bolt from the alternator
    • Attach a 14mm wrench to the serpentine belt tensioner
    • Use the wrench to loosen the belt
    • Pull the serpentine belt off the alternator
    • Release the tensioner
    • Remove the upper of the two 14mm bolts from the alternator
    • Pull off the fuse box cover
    • Remove the 10mm bolt from the fuse box
    • Lift the fuse box and pull it aside
    • Remove the lower of the two 14mm bolts from the alternator
    • Pry out your alternator with a pry bar
  4. step 4 : Removing the Catalytic Converter
    • Remove the four 10mm bolts from the catalytic converter heat shield
    • Lift the heat shield up and off
    • Apply penetrating oil to the five nuts at the top of the catalytic converter
    • Raise and secure the vehicle
    • Apply penetrating oil to the three 14mm nuts at the bottom of the catalytic converter
    • Remove the three 14mm nuts from the bottom of the catalytic converter
    • If the nuts will not come off, break them off with a torch
    • Lower the vehicle to the ground
    • Remove the five 14mm nuts from the top of the catalytic converter
    • Pull the catalytic converter up and off
    • Remove the gasket from the engine head
    • Clean the gasket mounting area with emery cloth or steel wool
  5. step 5 : Installing the New Catalytic Converter
    • Push the new gasket onto the engine head
    • Push the donut gasket into place
    • Put the new catalytic converter into place, lining up the studs
    • Line up the studs at the top of the catalytic converter
    • Start the five 14mm nuts at the top of the catalytic converter by hand
    • Tighten the five 14mm nuts to 45 foot-pounds of torque
  6. step 6 : Reinstalling the Alternator
    • Put the alternator into place
    • Start the lower 14mm bolt into the alternator
    • Insert the upper 14mm bolt into the alternator
    • Tighten the lower 14mm bolt
    • Insert the two 10mm bolts into the alternator
    • Put the alternator bracket into place
    • Connect the alternator wiring harness
    • Reconnect the wire from the battery to the alternator and tighten its nut
    • Move the fuse box into place
    • Insert the 10mm bolt into the fuse box
    • Push on the fuse box cover
    • Attach a 14mm wrench to the belt tensioner
    • Loosen the tensioner
    • Pull the belt onto the alternator
    • Release the tensioner
  7. step 7 : Reconnecting the Battery
    • Reconnect the negative battery cable
  8. step 8 : Reinstalling the Heat Shield
    • Put the catalytic converter heat shield into place
    • Insert the four bolts into the heat shield
  9. step 9 : Reinstalling the Oxygen Sensors
    • Insert the O2 sensors with the O2 sensor socket
    • Connect the O2 Sensor wiring harnesses
    • If you had to cut the old O2 sensors, you will need new ones
    • Put the engine cover into place
    • Insert the four 5mm Allen bolts into the engine cover
  10. step 10 : Fastening the Catalytic Converter
    • Raise and secure the vehicle
    • Start the springs and the 14mm nuts onto the bottom of the Catalytic Converter
    • Tighten the 14mm nuts until they bottom out

Tools needed for replacement

  • General Tools

    Jack Stands

    Floor Jack

  • Hex Wrenches

    5mm Hex Wrench

  • Pliers, Cutters & misc Wrenches

    Needle nose pliers

    Wire Cutters

  • Ratchets & Related

    A Piece of Pipe (for leverage)

    Socket Extensions

    Torque Wrench


    1/2 Inch Breaker Bar

  • Screwdrivers & Related

    Pry Bar

    Flat Blade Screwdriver

  • Sockets - Metric

    12mm Socket

    13mm Socket

    14mm Socket

    10mm Socket

    11mm Socket

  • Specialty Tools

    O2 Sensor Socket

    Acetylene torch

Installation Video
Watch video

Fits these Makes

Year Make Model Description
2002-2006Nissan Altima Nissan Altima L4 2.5L Exhaust Manifold Catalytic Converter Assembly
2002-2006Nissan Sentra Nissan Sentra L4 2.5L Exhaust Manifold Catalytic Converter Assembly

Part Interchange

Brand Label Part Number
DIY Solutions EXH00354

This item may be interchangeable with parts from other brands with the above part numbers. This information is provided only for reference and does not guarantee that the item you are purchasing is identical to parts with part numbers from the brands listed above. To confirm that this item fits your vehicle, use the above "Check Vehicle Fit" option.

In Stock
Part 1AEEM00620
Product Reviews
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4.64/ 5.0 44
Good experience dealing with 1aauto.
March 12, 2017
Catalytic Perfect fit. UIneeded the pulley off the tensioner and was able to replace the OEM unit. Car passed emissions testing with flying colors. Had a questiib and sent in an email. Had my response overnight. It was good to feel "they were there just a stone's throw away"
Fit perfact check engine light is off!!!
April 4, 2017
Arrived quickly, just as represented, fit perfact, the check engine light is now off. I would order again. These guys did great. Also had a warranty card with it. This huge all new bolts/nuts/gaskets came with it. Didn't need anything else to complete the repair.
great on line ordering
July 24, 2017
Got the part very fast and mechanic installed it right away. good on line ordering. love it you guys are quick and prices are good prices as well. next time if I need a part will order from you guys again. thank you for your services.
Perfect Fit
August 14, 2017
Needed to replace manifold due to bad threads for oxygen sensor replacement. Came complete and fit perfectly. A1 also offerered video for R&R of manifold. One of the best prices available, too.
August 14, 2017
Real easy to buy here and the price cheapest one can find and faster delivery ,
Very good part
August 18, 2017
Will refer people to a1 auto very fast delivery, and the prices are very reasonable
No better way to install something then with 1As Video
August 22, 2017
I originally changed out the OEM header for a catless header I got an Amazon for my 06 Nissan Altima, fearing that the OEM header would fail and destroy my engine as I have read over the internet. The troubles I began to get with engine codes were very frustrating, random and I was tired of trying to cheat the system to pass emissions testing. 1A Auto guarantees this built in cat header for up to 5 years and states that they have eliminated the cat failing problem with the OEM header, so I decided to give it a try. It has so far eliminated my engine codes and improved my gas mileage. The video they provided for the removal and installation of the header was in itself worth the 200 dollars as it helped me get the job done right the first time in around 4 hours with basic tools. Also, I ordered this part on a Monday after work and it was guaranteed by the following Tuesday but it came that same week on Friday. I was able to order it and install it within the same week.
September 2, 2017
My car need a new cataloytic converter. The car has 230k miles and it needed the new part. The part was easy to install took 2 hrs bc the main bolts were old. And now the car runs great ! It saves much more gas, better then what it used to be I'm probably at 27 mpg and before I was at 17mpg it's a big diffrents ! I highly recommend this part and it's also a good price!
Saved me $1000
September 12, 2017
Getting this part replaced at a muffler shop would have cost me over $1200. I am glad I found 1A Auto, because the part fit perfectly, came with all the necessary pieces, and the how-to video was amazing! Had it all done in a matter of hours. Some things to note: I had to completely remove the fuse box and engine coolant in order to remove the alternator on my 2005 Nissan Altima. Also, on the 2005 Nissan Altima, if you remove the heat-shield first you can remove the O2 sensor with just a wrench. And it really helps to have a really long handle for your ratchet set.
Perfect fit
October 13, 2017
This item was exactly what I needed. It fit perfectly in my 2006 Altima 2.5. The how to videos are really easy to follow and it showed me exactly what I needed to do. I've had the manifold in my car for a couple of weeks and my car is running great. I recommend switching out the Air/ Fuel ratio sensor along with the manifold to get the best performance out of your car. I'm very happy with the manifold and would strongly recommend it.
Altima Exhaust Manifold with Catalytic Converter Assembly
October 17, 2017
Perfect fit! And no more "Service Engine Soon" light. Good price. Arrived as promised. And thank you for the excellent video instructions!
The Best!!!
December 15, 2017
A while back, I bought this Exhaust Manifold from 1Aauto and it fit perfectly. My car has been running smooth. A local auto parts had it at $575 and a dealership at $700. Thank you all at 1Aauto!!! You guys are the best!
June 17, 2018
Reasonable price, free shipping, and the ability to pay with paypal! Shipping was fast! Would buy from this website again.
July 15, 2018
So far so good, this part arrived on time and when they said it would. Car is running good and no signs of any added repeats or work
Great deal
July 29, 2018
Same quality parts you find at AutoZone, Napa, Car Quest, etc., but for a lot less money. I recently discovered these bargains and will not go back to shopping at Oreilly's or any other store that over prices the merchandise.
Exhaust manifold
August 7, 2018
Looked everywhere for a quality replacement... “found it!â€� Welds were great and packaging was perfect! Thanks
Working will so,
September 20, 2018
I brought this manifold for my 2005 Nissan Altima. The merchant charged me 250$dollar put on my car. I must say working very will. 1.The part fits perfect on 2005 Nissan Altima 2,5 SL 2.My car run TO MUST SMOOTHER NOW. 3.The part came packed perfectly to my surprise two humps up for the packing
September 24, 2018
Right part at the right price, good quality, fast delivery
October 22, 2018
It works great on my nissan its saving a lot of gas too the best purchase I have made I do recomend this product
2002 Nissan Altima Exhaust Manifold
November 11, 2018
The manifold I bought from 1A Auto was great in many ways! Shipping was quick and arrived on time! The quality of the manifold looked to be just as good as my OEM manifold if not better. The improved design was comforting as well. I watched the installation video on YouTube and it really helped so I knew what to expect and how the parts should fit during the install. There could have been a few more details that I learned as I was working on my car but overall the video was a great intro so I wasn't flying blind. So far the manifold seems to be working great and I've had no issues. Thanks to 1A Auto for great overall service and I just have to stress the installation videos on YouTube are a great touch.
Great service
November 20, 2018
All parts came and it was delivered on time thanks for service will be using y'all again!!!
Cat change
November 27, 2018
To start I want to say that when I changed the catalytic converter it did what it is supposed to do. It not the original but, works just fine as an after market part. I was surprised I could get it this cheap.
Nissan upper catalytic converter replacement
November 30, 2018
Part was replaced to enable my car to pass local state emission test, was fairly easy to install and enabled my vehicle to pass the test
February 4, 2019
The service was great and the item arrived on the date promised. No issues with fix, perfect replacement. Came with all new hardware also.
Perfect buy
February 7, 2019
I brought it for my Nissan 2006 2.5s v4 engine vehicle. I had codes indicating catalytic converter not ready. I replaced upstream O2 in the beginning which haven't fixed the problem then I replaced the catalytic converter and all my codes where fixed and service engine light disappeared and never came back.. Cheers 1AAuto.com
Amazing Product
February 13, 2019
Before I bought this catalytic converter, my car would always delay acceleration. So I went on 1A Auto.com, and found a catalytic converter for an affordable price. After that, i took it to the mechanic, where it was installed. Before installing the converter, my service engine soon light was always on, and i didn't get enough performance out of my engine. After installing the converter, the car now runs smoothly, and the service engine soon light turned off. Without 1A Auto, my car life expectancy would drastically decrease, since it's a high mileage car.
New Cat.
February 15, 2019
New Cat had all of the parts promised, doughnut gasket for lower seal was damaged, due to poor packing , just thrown in bottom of box for shipping. Looks like the manifold hit it and tore a piece of it, had to get a new one from local store; 1a said to ship entire unit back and they would replace entire order, gasket cost way less than shipping. Installed cat with no problems so far. It's been a couple of weeks and all is good. Will buy more items from 1a as they become necessary, would recommend to a friend.
Catalytic converter
March 2, 2019
What a great price and everything was included making the job real easy saved houndreds of dollars buying from these guys
March 4, 2019
Direct fit awesome and cheaper than dealer .
Great product
May 16, 2019
They really a1 for real . I was very satisfied.
perfect fit!
August 6, 2019
works great!
Part fit great easy install
August 20, 2019
The part was easily installed. There were two issues I did have, one) was that the part had some shipping damage it was dented but still functional. Two) it did not have all the mounting points for the heat shields, so I was only able to put one of them back on. Which is the top one, the bottom one and the rear one did not have mounting fixtures. Other than that pretty much ok with the part. I will use 1A Auto again. As I do most all my own and some times others car repair.
Very pleased
August 26, 2019
Timely shipping and the part worked great.. very pleased with the whole process
November 14, 2019
Proactively swapped catalytic converter because of known issues with OEM part. Hadn't had issues until the new one was installed. Exhaust sturggles and had a missfire, teo issues that weren't present before. Install is air tight and done correctly. Part arrived with small crease in one of the manifold tubes, but it shouldn't cause problems like this. At best, part was sent with poor quality. At worst, part was sent as outright faulty.
Great product, great price
December 27, 2019
I've always been happy with the products I get from 1A and this manifold didn't disappoint. It came with all the necessary hardware, gaskets etc. Fit perfectly and no more check engine light due to catalyst failure. Will definitely order from them in the future.
quality part
January 20, 2020
So far fixed po240 code, part was as advertised I’m satisfied with purchase.
Fits Great and Enhanced the Power
Big Tater
April 9, 2020
Installed this with no issues other than the heat shield, which is my only complaint about the replacement part. Restored power back to the car that we haven't had in a little while, probably due to the cat having 200k miles on it. If you were looking to replace your cat or have a cracked manifold like I did you won't be disappointed if you purchase this unit. Good deal at a good price. Plus it always helps to have a useful video to help you get the job done! Nice job 1A Auto!
Great - full kit replacement
April 30, 2020
Full kit, bolts, gasket, etc- fit great. Quick delivery. Works great- my service engine light is no more.
I love it it’s perfect
May 6, 2020
The part is a perfect fit and it works well Also it’s way cheaper than autozone your spending hundreds of dollars at a regular auto store and this store your just paying less than $200
Nissan Exhaust Manifold
August 24, 2020
Product shipped fast and was exactly what I'd ordered. Manifold fit perfectly and had all of the required parts to get the job done. 1A also had a very helpful video for how to get the job done. Without the video I would have been lost. The only thing the video didn't cover has how to get stripped nuts off which I found out is a huge pain.
Manifold Exhaust Assembly
October 16, 2020
Part fits and my car and it runs great. Installed three weeks ago. Definitely would purchase again for 2006 nissan altima 2.5 engine
Catalytic converter 2005 Nissan Altima
November 23, 2020
Customer service was great, and that goes a long way with me. As far as the product so far so good. It was pretty straight forward and fit well. ( I actually previously bought a catalytic converter from another company that didn’t fit well so decided to go with 1aauto.) Right after installment my service engine light has also gone off. If I remember right you may need to save a couple original bolts from your old heat shield to attach to the new converter. Otherwise everything else was supplied. Once again customer service was great, and so far the product seems to be doing its job. I would recommend 1aauto to people without hesitation, and will probably do business with them again in the future myself.
Fits good, needs a better heat shield
December 25, 2020
The catalytic converter fits perfectly but it needs a larger heat shield. The small one that's integrated with it hardly covers anything. The header isn't even covered but I was able to take the old heat shield off of the defective cat and with holes drilled and bailing wire I made it work.
2006 Altima Catalytic Converter
March 9, 2021
Good price, fits well, straightforward install. The video that was emailed was a helpful touch. Service engine soon light is off so far. A little concerned about the difference in heat shielding compared to the original but was able to reuse the main shielding. The springs that were included did not taper and so when tightening the nuts, they collapsed inside of the springs. A bit of a pain to get back off. Considered using a washer, but decided to go with the original springs. So far, so good.
Customer Q&A
Does this product come with the 02 sensers?
March 8, 2016
March 8, 2016
No you have to buy it separately
March 8, 2016
No it doesn't come with an o2 sensor It does come with new bolts and gasket
March 8, 2016
March 8, 2016
What is the thread size of the O2 sensor?
October 18, 2016
Thread specs are unavailable. They are the same as the OEM and any other O2 sensor thread
October 18, 2016
Does it meet californias smog test ?
December 20, 2016
While this exhaust manifold with catalytic converter is made to meet California Emissions, this part is not C.A.R.B certified and will not pass the SMOG test in California or New York.
December 20, 2016
On my car the two bolt comes from behind this cat. Have two stud. Donuts gasket & nuts come with this cat for $230.95?
April 25, 2017
This will come with the cat and the gasket.
April 25, 2017
My 06 only has one o2 sensor while this one shows two. Is there a different manifold?
May 2, 2017
Yes it is two holes for sensors you plug one of them.
May 2, 2017
This comes with two plugs, so if you only have one sensor you just plug the other one!
May 2, 2017
There is only one O2 sensor in the manifold, the picture is just for reference, and I would recommend replaceing the O2 sensor (WKEOS00092) while you have it out. The heat shield is the only difference from the OEM manifold but it did not affect the fit at all.
May 3, 2017
i've been told that i need a catalytic converter w/manifold (front end) is this the correct part? for my 04 nissan altima?
June 3, 2017
Yes it is the correct part
June 3, 2017
Yes this is the correct part and will fit a 2004 Altima.
June 3, 2017
Yes, this part will be correct converter/manifold for a 2004 Nissan Altima 2.5L!
June 5, 2017
well I have a 2005 with the 4cly engine and it fit perfectly I hope this helps you. Sorry for the late reply.
June 6, 2017
Yes that is the correct part, I would recommend replacing the O2 sensor while its down (O2 sensor does not come with the manifold)
June 11, 2017
Yes, this product fits Nissan Altima models from 2002-2006, and the average installation time is about 2 hours.
February 13, 2019
My car has the PO420 code and it said Catalyst system bank 1 low efficiency. Is this the part i need ?
July 2, 2017
July 2, 2017
July 2, 2017
To fix this I replaced the catalytic converter
July 2, 2017
Romain - If your vehicle indicates other codes in addition to P0420, address them first as this may take care of the problem. Replacing the manifold/converter assy may resolve the issue, you may also be able to resolve the issue by just replacing the oxygen sensors. However there may be a quick inexpensive fix. About 8 months after replacing the converter/manifold on my 2003 Altima 2.5 I began getting code P0420 - the code indicates there is not enough variance between the upstream and downstream O2 sensors. I removed the downstream O2 sensor, installed an 18mm O2 bung/adapter, then reinstalled the O2 sensor. This moves the downstream sensor further from the exhaust stream, create greater upstream/downstream differential, and solved the issue. It's an inexpensive fix, quick to do and worth a try before doing more extensive repairs. Be sure to do it on the downstream sensor, NOT the upstream sensor or you will create other problems. Downstream sensor is the one further away from
July 3, 2017
My car doesn't have a 2.5 the bottom of it has 3 studs not 2?
August 28, 2017
This will not work.for.your vehicle
March 14, 2020
The exhaust manifold with the catalytic converter can not be used or shipped in the u.s?
April 7, 2019
This part can be shipped to every US state except California, New York and Maine.
April 7, 2019
I was told I need to replace my catalytic converter.. do I need to replace the manifold too?
April 24, 2019
There is a catalytic converter that is part of the manifold on this vehicle. There may be another cat on your vehicle on the exhaust system. Thanks!
April 24, 2019
It’s all one piece. Let engine cool all the way down before trying to remove manifold nuts. Stripped one and had to wait for the right tool to come in to complete the job.
April 24, 2019
is the cat california approved with ex.#?
May 20, 2019
This item is not CARB compliant.
May 20, 2019
Will this exhaust manifold after installed keep the check engine light off?
June 11, 2019
It will depend on the check engine light code. It could be the catalytic converter or the 02 sensor.
June 11, 2019
If this part is installed on a CA emissions model will the SES light come on?
October 13, 2019
Can’t help you Joe. My Altima was non-CA.
October 13, 2019
If your car was manufactured in California then you're going to have to put the catalytic converter made for your car, chances are it will throw the ses light, and then you would have to replace it again
October 13, 2019
The catalytic converter may have a light come on but it will not be able to pass inspection with that light. Please let us know if you have any further questions.
October 13, 2019
Hello my 2006 Nissan Altima has a check engine light on and I got two codes which are P0420 and P0128 what can I do? Please help I need to pass emissions
April 20, 2020
Thanks for your inquiry. There could be multiple reasons why you're having this particular problem. We suggest taking your vehicle to a nearby reputable shop to identify the cause. Once you know the cause, we'll be happy to see if we carry the parts and how-to videos needed for your repair.
April 20, 2020
Is this an OEM replacement part?
October 23, 2020
DIY solutions brand parts are manufactured by various aftermarket companies specifically for us and built to your vehicle's exact OEM specifications. This is an aftermarket part but will perform the same as the original.
October 23, 2020
Will this part need to be welded on?
December 14, 2020
Written and video installation instructions are found on the product page under the "How-To & Tools" tab. We're constantly adding new installation video instructions. If we do not have one for your vehicle on the product listing page, please check again at a later time or check our Video Library to see similar repairs here: https://www.1aauto.com/videos
December 14, 2020
No. I bolted everything back on with the included hardware, no welding needed.
December 15, 2020
Customer service


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2002-06 Nissan Altima Sentra Exhaust Manifold Catalytic Converter Assembly Cateran Inc-1AEEM00620 does not fit your:

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This part will only fit a 2003 Nissan Altima with these options.