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

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.

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

4.9 / 5.0
16 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Exhaust manifold
Looked everywhere for a quality replacement... “found it!” Welds were great and packaging was perfect! Thanks
August 7, 2018
1 month ago
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 Oreilly's or any other store that over prices the merchandise.
July 29, 2018
1 month ago
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
1 month ago
Reasonable price, free shipping, and the ability to pay with paypal! Shipping was fast! Would buy from this website again.
June 17, 2018
2 months ago
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
1 year ago
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
10 months ago
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. 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.
October 13, 2017
10 months ago
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
11 months ago
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!
September 2, 2017
1 year ago
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
1 year ago
Start typing your question and we'll check if it was already asked and answered. Learn More
Browse 8 questions Browse 8 questions and 20 answers
i've been told that i need a catalytic converter w/manifold (front end) is this the correct part? for my 04 nissan altima?
Sincere on Jun 3, 2017
BEST ANSWER: Yes that is the correct part, I would recommend replacing the O2 sensor while its down (O2 sensor does not come with the manifold)
My car has the PO420 code and it said Catalyst system bank 1 low efficiency. Is this the part i need ?
Romain H on Jul 1, 2017
BEST ANSWER: 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 the engine at the bottom of the manifold.
Does this product come with the 02 sensers?
Rawley F on Mar 8, 2016
BEST ANSWER: No it doesn't come with an o2 sensor It does come with new bolts and gasket
My 06 only has one o2 sensor while this one shows two. Is there a different manifold?
Andrew V on May 1, 2017
BEST ANSWER: 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.
WKEOS00092-O2 Oxygen Sensor
WKEOS00092-O2 Oxygen Sensor
My car doesn't have a 2.5 the bottom of it has 3 studs not 2?
Donald S on Aug 28, 2017
BEST ANSWER: If you have any questions regarding fit or are unsure of your options please contact our customer service department. 888-844-3393
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 on Apr 25, 2017
BEST ANSWER: This will come with the cat and the gasket.
Does it meet californias smog test ?
Juan Q on Dec 19, 2016
BEST ANSWER: 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.
What is the thread size of the O2 sensor?
Ray P on Oct 18, 2016
BEST ANSWER: Thread specs are unavailable. They are the same as the OEM and any other O2 sensor thread

Vehicle Fit

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

This part replaces:

  • OE # 140029J370
  • OE # 140029J305
  • Hollander 327-59373
  • Hollander 327-59374
  • Hollander 327-50120
  • Hollander 327-59243AB
  • Dorman 674-659
Part #: 1AEEM00620

Order must be placed by 4pm ET

Get it in: 2 - 4 Business Days

Want it sooner? Choose Next Day Air at Checkout

How-to Video:

(13:54 min)