2002-2004 Nissan Altima 3.5SE Exhaust HOW-TO Guide
II. Header Install
1. Product Selection
2. Removing Intake / Intake Manifold
3. Removing Stock Downpipe
4. Removing Manifolds
5. Extending O2 Sensors
6. Installing Aftermarket Exhaust Manifolds
III. Common Issues / Troubleshooting
1. CEL (Engine Code) Errors
This is a comprehensive guide to installing headers on a 2002 - 2004
Nissan Altima 3.5SE (VQ35DE). It will cover everything you will need to
know and how to perform certain tasks such as extending your O2 sensors
properly, fixing common CEL (Check Engine Light) problems, and what
tools you will need.
This is a project that can be done in your garage or driveway with a
friend or two (for emotional support, you'll need it). If you have done basic
bolt ons with any car and you have some socket wrench savvy in you, try it!
You will save yourself from spending $200-$400 to have a local shop do it.
Now that I've said that, you must have patience with this project. The engine
bay is tight to say the least and when you first look at things you will ask
yourself how in the bloody hell am I getting the stock manifolds out much
less getting these new manifolds in.
Now to the guide!
Generic Disclaimer: I am not responsible for any damage to your vehicle by following the instructions
below. This guide was produced for instructional use only; you may do things differently or have other
opinions which are welcomed. Revisions to this guide will be made over time, you may modify this guide as
you see fit. If you do duplicate this guide, please give credit to the author (Velicos@altimas.net). Please be
aware that this is NOT for the 2005+ Nissan Altima as the EGT system is completely different.
*Caution* - Be aware that the Stillen or Custom Enterprise downpipe is NOT compatible with the aftermarket headers.
Currently there are two products available for headers that supports our Altima. Here they
are in order by price:
---SS AutoChrome (aka XS Racing) Headers---
Price: $175.00 (Free shipping within the US)
Where do I purchase these?! eBay! UserID: "markracerx" who is an Altimas.net
member is a dealer for SSAC. He has a great reputation within the online community and
is extremely helpful in obtaining this kit. (The Altimas.net user name is MarkSpecV)
It will be posted with the title such as this:
"2002+ VQ35 3.5L V6 Altima XS Racing Headers Shpd. Free"
Positive: This product is an extremely low cost solution. If you are strapped for cash and
really want to go to the next level, use these. This is a replica version of the more
expensive Hotshot product. The welds are very professional and structurally the headers
are sound. Altima.net members have had great success with these headers. Also seems to
have very good fitment with our motors.
Negative: Where to begin... I'll just say that you always get what you pay for. All of the
hardware and accessories to help you extend O2 wires should be thrown out immediately.
The quality stainless steel is below par and will describe why discoloring and rust will
occur. The gauge of the steel used is pretty thin, so if you do not use the proper resonator
and muffler setup YOUR exhaust will sound like utter crap. The minimum resonator to
use is a 22” straight through and I strongly encourage a high flow catalytic converter for
reasons I will describe later.
Step 1) Throw out bolts, screws, washers, and lock nuts. Go to "Insert local hardware
store here" 1 and purchase stainless steel grade bolts of similar length to replace them.
Step 2) Throw out the cheap lamp wiring and go to "your local hardware store" and
purchase a grey colored cable with 4 (16 gauge) wires inside. Also has a ground wire
which you will discard when you extend your wiring harness (Red, White, Black, and
Green). Get 12-15ft of it, it's inexpensive and does the job well. Pickup medium and large
heat shrink tubing as you will need it. Also get plastic wire wrap to protect your wiring as
you route it from the O2 sensors to the connectors under the engine.
Step 3) Know that your pretty shiny headers will NOT be pretty and shinny in a week’s
time. They will discolor no matter what you do unless you coat them in some type of
ceramic or protective covering. This is up to you and I haven't experimented with this at
Conclusion: These by no means are cheap headers quality wise. The manifolds and
downpipe themselves are decent quality for what you pay for.
Price: $686 (Retail price on Hotshot.com)
Where do I purchase these?! You can get these from Mossy Performance ($635.00),
SportCompactOnline ($482.00 w/o cat, $617.00 w/ cat), and other places that sell any
Nissan Altima items.
I personally have not first hand seen these headers so I will bring up viewpoints from
other members that have been collected over the past year.
Positive: Extremely high quality ceramic coated headers made of stainless steel.
Negative: To my knowledge there aren't any negative aspects of this kit besides its price
compared to the SSAC headers. There have been a few complaints on fitment, although
I’m not 100% that’s true or not.
Conclusion: If you really love your Altima and have a couple bucks to spend and want
your investment to last you with minimal rust and deteriation, get out your wallet and
pick up a set. For the rest of us poor folk, the SS Autochrome headers are a bargain deal
for the same power gains.
1) ½” Socket Wrench
2) Metric Deep Sockets (10mm/12mm/14mm especially)
3) 12mm / 10mm Offset Wrench (Craftsman)
4) ½” Torque Wrench or Breaker Bar (Used to get leverage and torque to remove stock
manifolds and precats)
5) 12" ½” Socket extension and 3" 1/2" Socket Extension
6) Typical screw drivers, pliers, wrenches will be used from time to time
7) Hydraulic floor jack w/ 2x jackstands
8) Soldering iron, solder, and heat gun
9) Multimeter (Voltmeter)
10) PB Blaster (Oil Penetrate, loosens up rusted bolts. A must have!)
11) 22mm Metric Wrench (O2 sensors) and a tube of Anti-Seize
--Remove Intake and Intake Manifold--
1) Disconnect the negative cable to the battery and remove the plastic engine cover (4
2) Disconnect the MAF sensor and remove the intake entirely.
3) Remove the 12mm and 10mm bolt on top of your intake manifold and move the VIAS
solenoid and EVAP canister to the side (DO NOT DISCONNECT TUBES). After
removing the two devices, put both screws back into intake manifold so you will not
loose them. This will give you access to the main bolts below.
STOP – Checkpoint – STOP
To proceed, your engine bay must look like the following:
4) Now proceed to the rear left side of the intake manifold. You will two hoses connected
in the rear. Using pliers, remove the clamp and remove both tubes (Vacuum tubes).
Unplug the O2 sensor and remove the O2 sensor from the mounting bracket. There is a
nut next to the O2 sensor wiring harness, leave this alone as there isn’t sufficient room to
get to it yet (It will have to be removed, but after you remove the manifold from the
5) Behind the manifold on the right side there is a zinc bracket securing the rear of the
manifold to the engine block. You may remove it at the top of the bracket or remove the
bracket entirely (I recommend removing the entire bracket, gives you more room to
remove the rear manifold). Use a 12mm socket here, you can lean over from the right
hand side of the engine bay and extending your arm under the throttle body it will give
you access to remove the bolts. If you’re thinking owie my back, you haven’t seen
ANYTHING yet. Oh yeah, make sure you do like 10-15 minutes of warm up stretches
6) Remove the five main intake manifold bolts. Fairly simple….Nissan recommends you
to replace the gasket. I do not believe it is necessary but to be cautious pick one up at
your local dealership (They range between $12 and $18).
7) Now the manifold may be lifted up about an inch and you can pull it forward a couple
more inches giving you the required clearance to remove the rest of the wires and
electronics. Disconnect the green connector going into the throttle body and unbolt the
assembly the blue wiring harness plugs into by using a 10mm socket (move it away to the
side). There are two lines running into the bottom right of the intake manifold located
near the throttle body. Release the pressure by twisting the radiator cap. Remove each
line one at a time and use something to plug the line up so coolant doesn’t go all over the
place. I used two Bic pens to plug up the lines in both of my installs.
8) Now as all of the tubing and electrical connections to the intake manifold are removed,
you should be able to pull the manifold out with the canisters attached. Slowly do this,
just incase you missed something. Cover up your lower intake manifold ports with a
paper towel or shop rag. Your engine bay should now look like this:
--Removing Stock Downpipe—
1) Using a floor jack lift the car up to it’s maximum capability and secure the car with
two jack stands to ensure your safety. Just double check that the e-brake is secure and
you are on a hard level surface (such as your garage or driveway).
2) Using the breaker bar or torque wrench (14mm socket) remove the downpipe by
loosening the six nuts connecting the downpipe to the stock pre-cats. Remove the two
main bolts connecting the rear of the downpipe to the rest of the exhaust. The downpipe
will drop down and you can slide it towards the front of the car as it will be resting on it’s
--Removing Pre-Cats and Manifolds—
** Liberally soak the nuts and bolts visible with PB blaster to loosen them up now.
Slightly get the O2 sensors as they will be in there pretty tight as well**
Okay, here is my advice. Take a deep breathe and understand that this is the hardest part.
Once you have removed the stock manifolds you can claim victory that you’re a good
portion of the way home. This will be a frustrating few hours so grab a beer and take a
few breaks throughout the process. Also make sure your tetanus shots are up to date...
1) You need to un-bolt the heat shields on the front and back exhaust manifold. There are
three 10mm bolts that secure the heat shield. After you remove the bolts it takes some
wrestling to get it out of the rear. Don’t be afraid to start bending it a bit as it will be
discarded when you’re finished.
2) Remove the lower O2 sensors from the pre-cats using the 22mm wrench. Let the PB
Blaster sit there for a bit so you will lessen the chance of damaging the sensor. Treat
these sensors as your own child, they are bloody expensive and damaging them in this
process will cost you! (Each sensor goes for approx. $125+ at NAPA, I learned the hard
way). Don’t worry if you can’t remove these right now, you can remove them after you
remove the pre-cats.
3) Remove the upper O2 sensors from the manifolds using the 22mm wrench. Mark each
sensor for it’s proper location (Front/Upper, Rear/Upper, Front/Lower, Rear/Lower). Put
these aside, we will extend them later.
4) Unbolt the pre-cats from the exhaust manifolds by locating the 14mm bolts between
the two pieces. The front and rear should have bolts that you can remove from on top in
the engine bay and bolts you have to remove from below the engine bay. You can do this
easily by using a socket wrench, a 12” ½” extension, and a 14mm deep socket. Remove
both pre-cats and set them aside.
You will notice I don’t have many pictures here. This is due to increase in frustration and
just going along with the install. Don’t worry, just keep at it and it will happen. When you
think something can’t be done just start staring at it and the epiphany will eventually
smack you in the face.
5) Now it’s time to remove the front and rear manifolds as they don’t have O2 sensors in
them and no longer have the pre-cats connected. Everything is going to be done with a
12mm socket (Deep socket for the most part, a few you may have to get fancy with the
smaller sized 12mm sockets and accessories). Go bolt by bolt, six bolts in total on each
side. The AC compressor line gets in the way with the far left bolt on the front manifold;
you can bend this to the side safely to allow your socket to reach the bolt. To get to the
rear bolts, learn the art of engine climbing. I had to do this in order to gain access to the
rear bolts (This should NOT be done if you have a bad back or a history of back pain).
A) Learn how to engine climb = One knee on the battery and one by the grill.
B) Experiment heavily with different socket combinations.
C) Use the 10mm/12mm offset wrench here! It is required for a few bolts….
D) If you have children, give them earmuffs.
E) For the rear manifold you can’t see anything so it’s all played out by feel. Have a
friend get under the car (Don’t use your spouse or girlfriend, you will drop socket
wrenches on their face) and have them assist you with finding the next nut holding the
rear manifold on. This is the best time to ask your least favorite / expendable friend for
F) Remember, PB Blaster is your friend. Soak those suckers if they’re being stubborn.
--Extending O2 Sensors-- (Customized for the SSAC / XS Headers)
1) Measure how far you have to extend the length of each O2 sensor. You must extend
each one for the SS Autochrome headers. If you don’t, the connections are going to be
super tight and definitely not safe. Don’t mess around skimming over the little details as
they WILL be the ones to bite you in the ass in the days to come troubleshooting any
issues with your header installation. The front / upper O2 sensor is extended about 8-10
inches, same with the rear O2 sensor. This will give them enough slack to be routed and
zip tied properly. The rear O2 sensors need about six feet added to each. It is excessive
but required as I route them directly on top of my engine support brace. This will remove
them from any heat source or moving part, keeping them safe from the dangers of the
engine bay and outside elements. Oh yeah, go ahead and laugh at the wire that SSAC
supplied you to extend your sensors….
2) Remove the sheathing that exists (Blue lining in the above picture) using a razor blade.
This will expose the three wires you will need to extend. Using wire cutters, snip the
wires in the mid-section (Mark which white wire is witch [Tape the same white wire on
the end of the sensor and on the end of the connector so you can tell which white wire
goes to what one on the other side as this is important]). Cut the grey cable to length for
this sensor and remove about 1.5” of the cables jacket exposing 4 wires plus a ground.
3) Cut the ground and another colored wire (Your choice) as this is a 3 wire variation.
Now that you have your three wires, designate which wire will be used for what. I usually
did the marked white wire to red, black to black, and unmarked white to white. Now get
the soldering iron out and heat it up, have the solder handy too. Strip about an inch off all
the wires exposing the copper. Slip two pieces of the large heat shrink to the middle of
the grey cable so you may seal everything up when you’re done. Using the medium heat
shrink, put it over the individual wires so when you solder the wires together you can
heat shrink each individual section. Twist the wires together, it should form a tight and
4) Using the soldering iron, heat up the section of wire you wish to solder for a few
seconds. Take the solder and hold it on the wire you wish to solder, use the soldering iron
to melt the solder ONTO the wire and do this until a good portion of the wire is solid.
Give the section a few moments to cool down and give it a good tug, if it stays then good
job. Take the medium heat shrink and close up that individual wire with a heat gun.
Finish the other wires and heat shrink those as well. When you’re finished, use the larger
heat shrink and enclose the entire cluster. It should look something like:
--Installing Aftermarket Exhaust Manifolds—
1) Now it’s time to take your new headers and install them. Use the supplied gaskets with
the kit and install the new headers in reverse order of how you removed them. Get the O2
sensors in there as well (This may be done post install as well). Make sure to use anti-
seize lubricant on your O2 sensors! The bungs on the SS Autochrome headers will warp
extensively due to heat and will seize your sensor in a heartbeat.
2) Get the headers mounted up to the heads and hand tighten the nuts. As you’re sure the
O2 sensors placement isn’t conflicting with anything else go ahead and tighten it all
down. You will have to get creative with the 10mm/12mm offset wrench and the sockets
set you have. Take your time here; it is critical that you get a good seal as exhaust leaks
will be very problematic to you down the road.
3) As the headers are securely mounted and tightened down, it’s time to install the new
downpipe. With the SS Autochrome kit you are supplied with four gaskets (There are
different sizes!). Two have smaller internal diameters which are used between the
headers and the downpipe. The two larger inner diameter gaskets are used between the
downpipe and test pipe / test pipe and the stock exhaust flange to the rear exhaust. Finger
tighten all of the bolts to ensure proper fitment then torque everything down.
*These pictures do not reflect my final installation. I have since re-routed them
differently and I do not have pictures to reflect that currently. All of the grey wire is
covered with black wire loom to protect it from heat and the outside elements.
4) Install everything in reverse order. Make sure you re-install the intake manifold with
all of the vacuum lines and the two coolant lines as it was before. Re-connect the MAF
sensor as you install the intake and then finish it up by reconnecting the negative cable to
5) Turn the car on and immediately have a few people check your manifolds and
downpipe area for leaks. If everything checks out, good job! You’re done.
--CEL (Check Engine Light) Codes and Resolutions--
Front Upper O2 Sensor – HO2 Sensor 1 Bank 2
Rear Upper O2 Sensor – HO2 Sensor 1 Bank 1
Front Lower O2 Sensor – HO2 Sensor 2 Bank 2
Rear Lower O2 Sensor – HO2 Sensor 2 Bank 1
P0031 – Bank 1 / Sensor 1
P0051 – Bank 2 / Sensor 1
Cause: Heated oxygen sensor 1 heater control circuit low
P0032 – Bank 1 / Sensor 1
P0052 – Bank 2 / Sensor 1
Cause: Heated oxygen sensor 1 heater control circuit high
P0037 – Bank 1 / Sensor 2
P0057 – Bank 2 / Sensor 2
Cause: Heated oxygen sensor 2 heater control circuit low
P0038 – Bank 1 / Sensor 2
P0058 – Bank 2 / Sensor 2
Cause: Heated oxygen sensor 2 heater control circuit high
Fix: The extensions for the O2 sensors were not done correctly. Re-check your wiring to
ensure the connections and continuity is there. If the wiring is correct, assume bad O2
P0132 – Bank 1 / Sensor 1
P0152 – Bank 2 / Sensor 1
Cause: Heated oxygen sensor 1 circuit high voltage
P0133 – Bank 1 / Sensor 1
P0153 – Bank 2 / Sensor 1
Cause: Heated oxygen sensor 1 circuit slow response
P0134 – Bank 1 / Sensor 2
P0154 – Bank 2 / Sensor 2
Cause: Heated oxygen sensor 1 circuit no activity detected
P0138– Bank 1 / Sensor 2
P0158 – Bank 2 / Sensor 2
Cause: Heated oxygen sensor 2 circuit high voltage
P0139– Bank 1 / Sensor 2
P0159 – Bank 2 / Sensor 2
Cause: Heated oxygen sensor 2 circuit slow response
Fix: The extensions for the O2 sensors were not done correctly. Re-check your wiring to
ensure the connections and continuity is there. If the wiring is correct, assume bad O2
P0420 and P0430 - Catalyst system efficiency below threshold
Fix: Your ECU is detecting poor efficiency levels from the rear O2 sensors. There are
two solutions to this:
A) Purchase O2 simulators and connect them in parallel with the rear O2 sensors. Refer
to instructions of the O2 simulator for installation instructions. The rear O2 sensors are a
4 wire configuration.
B) This is the correct fix but involves some modification to your race cat. Cut off both
flanges of the SS Autochrome race cat (front flange connecting to the downpipe and rear
flange containing both O2 bungs that connects to the rest of the exhaust). Modify a high
flow catalytic converter (Ex. Megaflop 2.5” In/Out Catalytic Converter 94319) and weld
the flanges onto the cat. Trim to size as it will be different for everyone. After you have
put the high flow catalytic converter *before* the rear O2 sensors, the P0420 and P0430
error codes will go away on their own. Do not manually remove the codes; this will make
sure that the O2 sensors are working correctly if they go away on their own (Takes a few
hours of overall driving time).
Last Updated (5/14/2005) by Chris Teague (Velicos)
See more pictures of my install at -> http://www.altimafaq.net/personal