How hard is it to replace a catalytic converter on the 2004 titan

Just past the Cat converter on the tail pipe

Common Problems That Trigger the P0422 Code

Defective Catalytic Converter
Engine misfires have damaged the Catalytic Converter
Internal engine damage resulting in high oil consumption and/or a leaking Head Gasket has damaged the Catalytic Converter
Common Misdiagnoses

Oxygen Sensor(s) are replaced when the real problem is a damaged Catalyst
Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
Catalyst is replaced when a misfiring engine is the real problem

Catalytic Converter? - Nissan Titan Forum

www.titantalk.com > ... > Titan Performance Modifications
May 31, 2010 - 15 posts - ‎10 authors 2004-2006 4wd = 4 cats, you can remove (or gut) the two rear cats with no issues...just..... I have a 06 2wd I am about to do the exhaust. Hello Titan Owners! NEED HELP . Catalytic Converters ...
15 posts
Apr 25, 2014
Code P0420, Catalytic converters and exhaust system
9 posts
Jul 31, 2012
catalytic Converter going / Calif Emissions
12 posts
May 2, 2011
Catalytic Converter(s) bad
15 posts
Nov 20, 2009
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Check your fan clutch and make sure the radiator fins and condensor are clean so air flows freely. Also check the catalytic converter for restrictions. Hope this helps.

22mm or 7/8" Wrench

In the exhaust, next to converter
10 minute job

if the smoke is coming from the engine bay, check for spilt oil or an oil leak, especially on the exhaust. clean/fix this and the smoke should stop.

if it is coming from the exhaust, check you have used the correct grade of oil (too thin oil may bypass oil seals slightly) and you have not overfilled the engine and this can cause internal pressure, causing oil to bypass the seals, or even blow oil seals completely. overfilling will also damage the catalytic converter.

Follow the exhaust pipe to beyond the catalytic converter. The "rear" or down stream O2 sensor is usually on top of pipe behind the converter. Follow the wire from it to its disconnect plug andf unplug it. Use the correct size open end wrench to remove the sensor. Reverse to istall replacement. You really don't need a diagram - just your mark 1 eyeballs.

if you are wanting to replace yourself then you will need to cut in front and behind the catalytic converter, check the diameter of the pipe in and out... you may need to have the ends expanded a little to fit on your pipes. hope this helps

Catalytic Converter is part of your exhaust friend..... You'll probably have to replace the converter entirely