Moving the 2nd O2 sensor with catless header
 

Ok, here is the dealio. The OEM header with cat will be replaced with a catless header and tune using Ecutek architecture. It has two bungs to install O2 sensors. The plan is to use the 2nd bung for the O2 sensor #1. The OEM front pipe with cat will remain. I could Tig weld a bung just after that cat. O2 sensor #2 would go there (with the wires extended). The tune would be set up to NOT suppress the CEL for Cat function (I think it is p0420)

So I would end up with a sensor upstream and downstream of the remaining cat.

The reason I do not want the CEL suppressed is that the OBD2 readiness monitor for cat function will never go to a ready state if the tune suppresses the CEL. In NYS the annual DMV inspection will only allow you 1 "not ready" monitor.

I do not want to spend a day every year screwing around swapping the system back and forth and reflashing the ECU.

Has anyone done this and made it work (No CEL AND no more than 1 monitor pending?)

https://i.imgur.com/XLb51rJ.jpg

can someone help me get the image to show?:bonk:

Put [img]link to pic[/img]

Or even easier click the add photo button and paste the link in the box.

https://i.imgur.com/XLb51rJ.jpg

Why not just use the two standard bungs in new catless header, but install an 02 spacer in rear 02 sensor.


much less hassle and will have about the same chance of wrking as moving the rear 02 sensor.


the ecu is looking for specific readings from the sensors anything but stock cat may trigger CEL P0420




https://www.ebay.com.au/sch/i.html?_...pacer&_sacat=0

That would work. It shouldn't matter which one you use for the primary O2 sensor, but depending on the manifold design you would want the one after all runners have merged and if both are after the merge the one closer to the engine is preferable.

I moved the rear sensor on my old Sentra Spec V with hair dryer wire... Worked perfectly. We cut a bung off the stock header, punched a hole behind the 2nd cat, which was an aftermarket high flo cat, and welded it on. Then extended the wire for the 2nd sensor with hairdryer cord and it never gave me a CEL.