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Emissions Regulations: This product is not C.A.R.B. (California Air Research Board) approved.
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Install Tip: You may be required to reset the vehicle computer after installation of this part.
Item Condition:New
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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.
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.
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How to Replace Catalytic Converter 2001-05 Honda Civic
Created on:
Tools used
12mm Socket
13mm Socket
Hammer
Socket Extensions
14mm Socket
8mm Allen Wrench
O2 Sensor Socket
Bungee Cord
22mm Wrench
Ratchet
11mm Socket
13mm Wrench
1. Removing the O2 Sensors
Loosen the rear O2 sensor with an O2 sensor socket or 22mm wrench
Twist the O2 sensor off by hand
Allow the sensor to hang
Loosen the front O2 sensor with an O2 sensor socket or 22mm wrench
Unclip the O2 sensor wiring harness from its keeper
Twist the O2 sensor off by hand
Allow the sensor to hang
2. Removing the Catalytic Converter
Apply rust penetrant to the 12mm bolts on the exhaust manifold flange
Remove the two 12mm bolts from the exhaust manifold flange
If the bolts are corroded, use a hammer to tap on an 11mm socket
Support the tail pipe with a bungee cord
Remove the three 13mm bolts from the tail pipe flange
Allow the front of the catalytic converter to hang
Pull the catalytic converter off its rubber bushing
3. Installing the Catalytic Converter
Remove the plugs from the two O2 sensor bungs with an 8mm Allen wrench
Hang the catalytic converter from the rubber bushing
Insert the exhaust gasket into the exhaust manifold with the thinner side at the bottom
Lift the catalytic converter to meet the exhaust manifold
Start the two 14mm bolts into the exhaust manifold flange
Insert the gasket into the rear of the catalytic converter
Insert the three 13mm bolts into the tail pipe flange
Remove the bungee cord
Tighten the two 14mm bolts in the exhaust manifold flange
4. Installing the O2 Sensors
Start the front O2 sensor by hand
Tighten the front O2 sensor with an O2 sensor socket or 22mm wrench
Clip the O2 sensor wire into its keeper
Start the rear O2 sensor by hand
Tighten the rear O2 sensor with an O2 sensor socket or 22mm wrench
Run your car and listen for exhaust leaks
Clear your ECU code or have a shop do so if necessary
Brought to you by 1AAuto.com, your source for quality replacement parts and the best service on the Internet.
Hi, I'm Mike from 1A Auto. I hope this how-to video helps you out, and next time you need parts for your vehicle, think of 1AAuto.com. Thanks.
In this video we're going to show you how to replace the catalytic converter in your 2003 Honda Civic 1.7 VTEC EX model. The items you'll need for this repair are a new catalytic converter from 1AAuto.com; 11, 12, 13, and 14-millimeter sockets; a ratchet and extension; a 13-millimeter wrench; an O2 sensor socket or a 22-millimeter wrench; an 8-millimeter Allen wrench; a hammer; and a bungee cord.
The catalytic converter is located underneath the center of the vehicle on this Honda EX model. All other models are located on the header.
We're going to remove the rear O2 sensor using an oxygen sensor socket. You can also use a 22 millimeter wrench. Watch the wires when removing to make sure that they don't twist up and break. Otherwise you'll have to unplug the sensor. Once the sensor is cracked loose, you should be able to remove it by hand. Allow that to hang out of the way.
Use that same O2 sensor socket to remove the front O2 sensor, which is located at the bottom of the exhaust manifold, and the top of the pipe to the catalytic converter. You may have to remove the keeper for the wiring harness here in order to get enough slack to remove it without having to disconnect the connector. Allow that too to hang out of the way.
We're going to remove the two spring bolts securing the flange for the catalytic converter pipe to the bottom of the exhaust manifold. I believe at one point they were 12-millimeter socket but ours have corroded down so we're going to use an 11 millimeter socket and tap it on with a hammer. Now carefully try to remove the bolt with a socket and ratchet. We've soaked ours in penetrating oil, but there's still a good chance that these bolts are going to break so it's a good idea to have replacements on hand. We'll try a 12 millimeter socket on this one now.
At the rear of the pipe remove the 3 bolts connecting the cat flange to the tail pipe flange. You'll need a 13 millimeter wrench to support one side while you remove the other with a 13 millimeter socket and ratchet. Before removing the last bolt, you may want to use a bungee cord to hang the tailpipe so it doesn't fall out after you've removed all the hardware. Allow the front of the cat to hang down and remove the hanger from the rubber bushing.
Here we have our old part that we removed from the vehicle and our new part from 1AAuto.com. See there are some minor aesthetic differences between the two, but they are going to both work just fine. See we have the same two bolt flange at the top. They look a little different, but these hangers line up to the same place. These tabs here are most likely where the heat shield used to mount up to this catalytic converter. As you can see our new one is welded on nice and sturdy, and a nice fresh three bolt flange is exactly what this one used to look like. The catalytic converters are the same in both size and composition. They come with a new bung for the O2 sensor on the cat itself, as well as on the up pipe to the exhaust manifold.
The reason we replaced our old catalytic converter is because our vehicle had the check engine light code PO420 which is a catalyst system efficiency below threshold on bank 1. This is a 4-cylinder vehicle, so it only has one bank. It is true that this code as well as many other codes can be caused by the catalytic converter. It could also be a fuel system rich or lean as well as an O2 issue. We went through and checked everything, all our O2 sensors were new, everything else works, so we narrowed it down to having to replace our catalytic converter. Another couple of symptoms that your catalytic converter has gone bad are poor fuel economy, or power, or high under hood, or exhaust gas temperatures. As this clogs up the exhaust fights harder and builds up in the system and creates more heat. In this case it actually melted some plastic components under our engine. So if your old catalytic converter is clogged or malfunctioning causing check engine lights and emission related codes or high under hood temperatures as well as high exhaust gas temperatures, loss of power or loss of fuel economy, then this new catalytic converter from 1A Auto is going to go in direct fit, just like your original equipment, get your car running clean and right again, and fix you up right.
Before installing our new catalytic converter into the vehicle we'll have to remove these plugs in the O2 sensor bungs. To do this you'll need an 8-millimeter Allen key. Remove the one in the top of the catalytic converter as well as the one below the two bolt flange where it bolts up to the exhaust manifold.
Reinstall our catalytic converter into the hanger. Install this conical exhaust gasket onto the bottom of the exhaust manifold with the thinner end of the cone facing down. Set the flange into place. Install our new spring bolts. Install the gasket into the rear flange. Install your three 13 millimeter bolts. Once you've started your bolts you can remove the bungee cord and tighten down the hardware with a 13 millimeter socket ratchet and wrench.
The new hardware is 14 millimeter so we'll use a 14 millimeter socket ratchet and extension to tighten the flange back to the exhaust manifold. What I like to do with these O2 sensors – as you can see the wires are already twisted up a little. What we're going to do is we're going to spin this sensor counterclockwise, which means when we spin it in and tighten it up clockwise it will reduce the stress on our wires.
Bring it down as tight as you can by hand. Finish tightening it with an O2 sensor socket or a 22 millimeter wrench. Repeat these steps for the rear O2. If you had to remove your wire harness from its clip, reattach it now.
Fire up your car. Make sure that the exhaust system is free of leaks, it sounds correct. Then erase the code from the ECU if you're able to do so yourself, or go to your nearest professional or parts dealer to have the codes erased from the ECU.
Thanks for tuning in. We hope this video helps you out. Brought to you by www.1AAuto.com, your source for quality replacement parts and the best service on the Internet. Please feel free to call us toll-free, 888-844-3393. We're the company that's here for you on the Internet and in person.
EXH00061
In Stock
Product Reviews
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4.58/ 5.012
12 reviews
5 Stars
4 Stars
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1 Star
10
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OE fitment and great product
Matthew
February 26, 2017
This fit just like stock and included all hardware needed. Great product and would recommend to anyone!
Good Stuff!!!
John
July 10, 2017
Great direct replacement part for my 2003 Honda Civic. Though, I did have to buy new bolts and nuts for the end that connects to exhaust, manifold spring bolts where included. The original bolts was welded on the old cat-converter. Picked those items at my local auto store. No big deal, preferred new ones anyway. The instructional vid 1A Auto produced is awesome. That vid prompted me to purchase this part and do-it-myself. My only suggestion to 1A Auto would be to included to the '3" each nuts and bolts for the exhaust end. :)
02 Civic catalytic converter
G
February 15, 2018
Showed up pretty quickly fit in without trouble $100 cheaper than what the garage wanted to charge and they put it in anyway
Perfect Fit Replacement
Michael
February 24, 2018
$100 cheaper than anything else I could find. This is a true direct replacement. Installation was easy and the fit was perfect. You will probably need to replace the three bolt in the rear flange, but this item does not include these (my three bolts were so rusted that two had to be cut off and the third wasn't worth reusing). The front (manifold) bolts were included.
Perfect fit!
B
October 3, 2018
The part arrived very quickly and with free shipping. The part fit great and was much cheaper than what other places were charging. The gasket didnt fit, but it was only $7 to get the right one from a local auto shop. I will definitely buy from 1A Auto in the future if I need car parts.
Good quality, good price, thanks
D
November 19, 2018
I would highly recommend this catalytic converter. It was a direct bolt on replacement for my 01 Honda Civic and fit perfectly. No problems, no modifications. Fixed my check engine light emissions code that wouldn't go away. Price was reasonable and shipping was quick. A well made product that functions as it should.
Good quality product
Kenrick
February 24, 2019
Fast shipping
P
July 19, 2019
Great service at a great price. I'm very satisfied with my purchase of the catalytic converter the car runs great thanks to 1 A Auto
Not As Shown
Jean
February 20, 2022
Product does not look like the image or what is shown in the installation video. No threaded inserts to protect sensor ports. Flanges covered in surface rust. No heat shield or mounting means for factory heat shield. I ended up wrapping it. Crush washer for downstream flange was the wrong size. Final fit wasn't exact. The rubber dampener is fully compressed and I had to bend the heat shield (on the car) to make room for the O2 sensor.
Just disappointed. Don't market one way and deliver on another. Will not ever purchase from 1A again.
Need new bolts too
Andy
August 25, 2022
Its good but new bolts just be added to the orders
Be careful with manifold bolts.
Drew
November 19, 2022
It fits although if your manifold bolts are rusty they might not fit or they will strip with this thicker flange. I stripped the threads on the manifold and had to retap them, then buy the 2 new bolts from Honda. $33 bucks each. Then once I started he car I got a code that the o2 sensor was faulty. Never got that code before with the old cat. Oh well. Still cant pass inspection so here I am. But my old cat had holes so I dont smell exhaust anymore!
Be careful with manifold bolts.
Drew
November 19, 2022
It fits although if your manifold bolts are rusty they might not fit or they will strip with this thicker flange. I stripped the threads on the manifold and had to retap them, then buy the 2 new bolts from Honda. $33 bucks each. Then once I started he car I got a code that the o2 sensor was faulty. Never got that code before with the old cat. Oh well. Still cant pass inspection so here I am. But my old cat had holes so I dont smell exhaust anymore!
Customer Q&A
Will this part fit on a 2002 Honda Civic Si 1.7l?August 11, 2018
L U
10
Hello,
This part is listed to fit 2001-2005 Honda Civic EX model only. Thank you!
August 11, 2018
Adam G
Why does the description say it's C.A.R.B legal for California but in the warranty and emissions section it says it's not?November 18, 2018
Antonio S
10
The parts are unable to be shipped to California or New York due to having different emission standards.
November 18, 2018
Emma F
Is this catalytic converter compliant with CA emission laws and can it be shipped here ?March 23, 2020
Richy J
10
Thank you for your inquiry! Due to state emissions regulations we cannot ship this item to California, as it is not California Air Research Board approved. Please let us know if you have any further questions, thank you!
March 23, 2020
Jessica D
Is this for the '04 civics with the vtec engine (D17A2)?October 28, 2020
David R
10
This is for the EX model with a 1.7L engine only.
October 28, 2020
T I
Does this come with both gaskets and the two spring bolts?December 18, 2020
Benjamin T
10
New hardware is not included with this item. You may be able to reuse your original hardware if it is in good condition.
December 18, 2020
Emma F
Does this catalytic converter fit an 2002 civic coupe lx?December 29, 2020
Joe S
10
This will only be correct for a 2001-2005 Honda Civic EX L4 1.7L, it will not work with your LX.
December 29, 2020
I P
Does this part fit a 2002 civic coupe lx ?December 29, 2020
Joe S
10
This is not the correct part for your vehicle, but we do carry the one you need. The correct part number is: 1AEEM00612
December 29, 2020
T I
Does this part fit a 2002 civic coupe lx ?December 29, 2020
Joe S
10
This kit is not listed to fit the LX model.
December 29, 2020
Jessica D
Does this fit on a 2005 civic lx 4 door?October 22, 2021
John D
10
No, only an EX.
October 22, 2021
Eric T
10
Currently, we do not carry this part for your vehicle. We're always updating our inventory so please check back soon!
October 22, 2021
Emma F
Is the catalytic converter legal in California??October 27, 2021
Jesus G
10
We cannot ship this item to California or Colorado, as it is not California Air Research Board approved.
October 27, 2021
T I
Can I use this item in California? To pass smog check?October 30, 2021
Erick P
10
CARB emission laws prohibited us from shipping catalytic converters to the state of California.
October 30, 2021
Ricale A
Is this converter New York State complaint?February 4, 2022
John D
10
It can only be installed on a vehicle with Federal Emissions in the state of New York.
February 4, 2022
Andra M
PUEDO USAR ESTE ARTICULO PARA QUE MI AUTO PASE LAS EMISSIONES EN CALIFORNIA ?June 7, 2022
John D
10
We cannot ship this item to California, as it is not California Air Research Board approved.
June 8, 2022
T I
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