Last Updated: 02/04/2018 @ 09:24 pm

When Maxima owners get the infamous P0420 check engine light code for bad pre-cats, the best route is to go with eBay headers. However, when you search eBay there are various types of header listings that pop-up. This post goes into a little more details about what modification are required on the different types of available eBay headers.

The headers on eBay are listed as VQ35DE Altima 3.5 headers. They will work fine on all 2004-2008 6thgen Maxima’s.

So which headers should I buy for my Maxima?
We would recommend going with the Manzo headers for either 6-Speed or Automatics.

General Information:

Inlet: 2″
Outlet: 2.5″
Made of High Quality T-304 Stainless Steel Material
Mandrel Bent Tubing & CNC Machined Flanges

Modification For Automatic:

You will need to shave down the flange on the header. You do not need to shave the starter as some have done but also an option. We recommend the flange itself.
The y-pipe for these Manzo headers do sit low, so many members modify it to lift it up a bit.
Weld bungs for secondary O2 Sensors. There are two sensors. You also need to extend the harness.
Weld in EGR Bung on Rear Header
- If you are tuning with UpRev, then you can block off your EGR with a plate and have it tuned. You can get the EGR block-off plate from NWP Engineering for $35.00.
- When properly tuned it will not throw a code. You can also add a resistor in the EGR temp sensor.

Modification For Manual:

OBX Headers are pretty much plug-n-play.
Manzo/Generic Brand Headers requires O2 bungs for secondary sensors. There are two sensors. You also need to extend the harness.
Weld in EGR Bung on Rear Header
- If you are tuning with UpRev, then you can block off your EGR with a plate and have it tuned. You can get the EGR block-off plate from NWP Engineering for $35.00.
- When properly tuned it will not throw a code. You can also add a resistor in the EGR temp sensor.

Extending O2 Sensors harness:

You have two options for the o2 sensors. Option is to buy the 350z o2 sensors which have a longer harness that does not need to be modified. For option 2, -f your current sensors are good and you don’t want to buy the 350z sensors you can splice you can work with existing sensors. For O2 sensors, you can either extend your existing ones or get the 350z sensors which are already extended from factors. We recommend extending the O2 harness itself versus the O2 sensor wire themselves. Many people have had success with splicing the O2 sensors with no issues given the same wire gauge was used.

Here’s some of main reason why techs do not recommend splicing the O2 Sensor Pigtails.

The O2 Sensor wire is a signal wire and very sensitive.
The O2 sensor wire is made up of material like aluminum or stainless steel and will not solder properly like copper.
Even if you manage to solder the wires, it may possibly give you weird or inaccurate readings.
By cutting/soldering/extending, you are disrupting its original properties which can be potentially sending “altered” input signals to the ECU. This can result in bad readings thus triggering additional CEL codes.
The wires are not color-coded so you have to be very careful where you splice to. The harness clip is color-coded and makes it easier to determine which wires match up to each other.