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

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Vehicle Fit

Our aftermarket manifolds are some of the highest quality replacements on the market!

If your vehicle's exhaust is getting loud and the exhaust noise is coming from under the hood or engine then you may need to fix a cracked exhaust manifold. Replacing a broken manifold is easiest with a direct replacement manifold that will fit correctly and bolt up to you original engine and exhaust system. This manifold is a direct fitting replacement.

This steel exhaust manifold with catalytic converter has been designed to eliminate the faults of the original Nissan design. This exhaust manifold has the following specifications:

  • New 1 piece design with new catalytic converter (not reconditioned)
  • Direct replacement
  • Corrosion resistant
  • Replaces original manifolds that are cracked from thermal expansion and contraction
  • Strengthened and redesigned in the vulnerable areas of failure
  • Fits both standard and automatic transmission models
  • Only fits 2.5L vehicles with or without California Emissions

Now you can buy a high quality exhaust manifold with catalytic converter that is built to strict quality control standards for almost less then 1/2 the price at the dealer. REPLACE your broken, warped, or cracked exhaust manifold now with this great fitting, alternative. This exhaust manifold with catalytic converter is a great replacement and has substantial cost savings over a dealer unit.

Emissions Note:

Due to state emissions regulations, we cannot ship this item to the state of California as it is not C.A.R.B ( California Air Research Board) approved for use in this state.

Due to New York state emissions regulations, this item cannot be installed on a California emissions equipped vehicle in the state of New York.

All emissions information for a vehicle can be found on a tag under the hood. If the tag is missing, you can contact a dealership with your VIN to determine which emissions system your vehicle is equipped with.

Item Condition: New

5 Year Warranty

This item is backed by a 5 Year Warranty. In the event this item should fail during intended use, we will exchange the part free of charge (excludes shipping charges) for the original purchaser. 

  1. step : Disconnecting the Battery (0:59)
    • Disconnect the negative battery cable with a 10mm socket and ratchet
  2. step : Removing the Oxygen Sensors (1:10)
    • 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 : Removing the Alternator (3:15)
    • 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 : Removing the Catalytic Converter (5:47)
    • 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 : Installing the New Catalytic Converter (8:46])
    • 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 : Reinstalling the Alternator (10:05)
    • 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 : Reconnecting the Battery (12:03)
    • Reconnect the negative battery cable
  8. step : Reinstalling the Heat Shield (12:10)
    • Put the catalytic converter heat shield into place
    • Insert the four bolts into the heat shield
  9. step : Reinstalling the Oxygen Sensors (12:28)
    • 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 : Fastening the Catalytic Converter (12:57)
    • 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:

    Allen Wrenches

  • 5mm Allen Wrench

  • General Tools

  • Floor Jack
  • Jack Stands

  • Pliers, Cutters & misc Wrenches

  • Needle nose pliers
  • Wire Cutters

  • Ratchets & Related

  • 1/2 Inch Breaker Bar
  • Socket Extensions
  • A Piece of Pipe (for leverage)
  • Torque Wrench
  • Ratchet

  • Screwdrivers & Related

  • Flat Blade Screwdriver
  • Pry Bar

  • Sockets - Metric

  • 13mm Socket
  • 11mm Socket
  • 10mm Socket
  • 14mm Socket
  • 12mm Socket

  • Specialty Tools

  • Acetylene torch
  • O2 Sensor Socket

4.78/ 5.0
23 reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Good experience dealing with 1aauto.
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 stones throw away"
March 12, 2017
Fit perfact check engine light is off!!!
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. Didnt need anything else to complete the repair.
April 4, 2017
great on line ordering
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.
July 24, 2017
Perfect Fit
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 ,
August 14, 2017
Very good part
Will refer people to a1 auto very fast delivery, and the prices are very reasonable
August 18, 2017
No better way to install something then with 1As Video
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.
August 22, 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 Im probably at 27 mpg and before I was at 17mpg its a big diffrents ! I highly recommend this part and its also a good price!
September 2, 2017
Saved me $1000
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.
September 12, 2017
Perfect fit
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. Ive 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. Im very happy with the manifold and would strongly recommend it.
October 13, 2017
Altima Exhaust Manifold with Catalytic Converter Assembly
Perfect fit! And no more "Service Engine Soon" light. Good price. Arrived as promised. And thank you for the excellent video instructions!
October 17, 2017
The Best!!!
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 $700. Thank you all at 1Aauto!!! You guys are the best!
December 15, 2017
Reasonable price, free shipping, and the ability to pay with paypal! Shipping was fast! Would buy from this website again.
June 17, 2018
So far so good, this part arrived on time and when they said it would. Car is running good and no signs of any added repeats or work
July 15, 2018
Great deal
Same quality parts you find at AutoZone, Napa, Car Quest, etc., but for a lot less money. I recently discovered these bargains and will not go back to shopping at Oreillys or any other store that over prices the merchandise.
July 29, 2018
Exhaust manifold
Looked everywhere for a quality replacement... “found it!� Welds were great and packaging was perfect! Thanks
August 7, 2018
Working will so,
I brought this manifold for my 2005 Nissan Altima. The merchant charged me 250$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 20, 2018
Right part at the right price, good quality, fast delivery
September 24, 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
October 22, 2018
2002 Nissan Altima Exhaust Manifold
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 wasnt flying blind. So far the manifold seems to be working great and Ive 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.
November 11, 2018
Great service
All parts came and it was delivered on time thanks for service will be using yall again!!!
November 20, 2018
Cat change
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.
November 27, 2018
Nissan upper catalytic converter replacement
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
November 30, 2018
Will this fit my car? Add a vehicle to make sure
Customer Q&A
Ask a question to 1A Auto customers who purchased the product
Does this product come with the 02 sensers?
Rawley F March 8, 2016
Chassiti B March 8, 2016
No you have to buy it separately
Blayn S March 8, 2016
No it doesnt come with an o2 sensor It does come with new bolts and gasket
Dante G March 8, 2016
Brian F March 8, 2016
What is the thread size of the O2 sensor?
Ray P October 18, 2016
Thread specs are unavailable. They are the same as the OEM and any other O2 sensor thread
Brian F October 18, 2016
Does it meet californias smog test ?
Juan Q 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.
Alex P 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?
Andrew W April 25, 2017
This will come with the cat and the gasket.
Derek C April 25, 2017
My 06 only has one o2 sensor while this one shows two. Is there a different manifold?
Andrew V May 2, 2017
Yes it is two holes for sensors you plug one of them.
Pete M May 2, 2017
This comes with two plugs, so if you only have one sensor you just plug the other one!
Tim K 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.
David M May 3, 2017
ive been told that i need a catalytic converter w/manifold (front end) is this the correct part? for my 04 nissan altima?
Shaquana S June 3, 2017
Yes it is the correct part
Pete M June 3, 2017
Yes this is the correct part and will fit a 2004 Altima.
Norberto C June 3, 2017
Yes, this part will be correct converter/manifold for a 2004 Nissan Altima 2.5L!
Tim K 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.
Mary E F 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)
David M June 11, 2017
My car has the PO420 code and it said Catalyst system bank 1 low efficiency. Is this the part i need ?
Romain H July 2, 2017
Debora L July 2, 2017
Nathan V July 2, 2017
To fix this I replaced the catalytic converter
David R 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. Its 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 the engine at the bottom of the manifold.
James B July 3, 2017
My car doesnt have a 2.5 the bottom of it has 3 studs not 2?
Donald S August 28, 2017
Year Make Model Description
2002-2006Nissan Altima Nissan Altima Exhaust Manifold with Catalytic Converter Assembly L4 2.5L
2002-2006Nissan Sentra Nissan Sentra Exhaust Manifold with Catalytic Converter Assembly L4 2.5L
Part #: 1AEEM00620

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How-to Video:

(13:54 min)