With so many Nissan Patrol Y62 owners having the P0420 Code appear...your dealer or mechanic will likely advise that you need to replace the front left and right Catalytic Converters, which also include the manifold assembly.
Lets firstly walk through a couple of Frequently Asked Questions on the replacement manifolds with incorporated catalytic converters
Why does my Y62 Patrol have the P0420 Code appearing?
The Code P0420 stands for “Catalyst System Efficiency Below Threshold (Bank 1).” This code indicates that your vehicles computer [ECU] has detected underperformance from either left or right hand Bank 1 catalytic converter. A faulty catalytic converter is the most frequent cause of a P0420 trouble code so its highly probable that the catalytic converters need replacing and for the Y62 Patrol the Bank 1 units include the manifolds so the only unit needs to be replaced.
Do these replacement manifolds improve the performance of my vehicle?
No these Y62 replacement manifolds by Rhino Exhaust are a 'like for like' replacement to the genuine Nissan manifolds. Whilst they might improve your vehicle performance if your catalytic converters are blocked or damaged - these manifolds are not any larger in pipework size.
Are they a direct replacement with no cutting or welding required?
Yes the Rhino Exhaust replacement Y62 manifolds are a direct replacement to the Nissan OEM product and no modifications are required during the installation.
Do the Rhino Exhaust replacement manifolds include the catalytic converters?
Yes they include the catalytic converters within the manifolds assembly. You can see the catalyst from the two bolt outlet flange
Why is it necessary to have the catalytic converters within the manifold?
The reason its necessary to have the catalysts within the front manifolds is because the Y62 Exhaust design has emission sensors before and after the catalytic converters. If you remove these catalytic converters you basically need to do a complete ECU remap to override the sensors. This is largely unfavorable as its costly and will often void manufacturers warranty
Why do the manifolds have sensors on them and what do they do?
These sensors tell the ECU about the emission performance of the engine and as the manifolds on the Y62 incorporate the catalytic converters, if over time the catalysts have become burnt out or lost their coating, then the performance will be below the required legal emission reduction threshold and this will send a signal to the ECU which brings up an engine light on the dash. This is often the reason why we know that the units require replacing.
The below image is of the factory Nissan manifolds with the incorporated catalytic converters
Now the other alternative is to replace your Y62 V8 left and right factory manifolds with Performance Extractors Headers however there are some pro's and con's that are at times overlooked in taking this option
Firstly, the extractors performance headers eliminate the front catalytic converters and are replaced with pipework as shown in the comparison image below
Whilst this free flow design and larger pipework will improve exhaust flow on the big 5.6L V8 and subsequently result in more torque and power, in removing the catalysts, it will also throw up the P0420 Code, as the ECU has recognized that there are no catalytic converters reducing the emissions.
This is when the vehicle needs an ECU remap to override the sensors. Whilst that might be fine for some motoring enthusiasts depending on your vehicle use, it will often result in Nissan putting a line through your factory warranty as you have a) removed an emission reduction device and b) you have reset the ECU parameters.