Apologies if there is another post about this, but my research didn’t show much for this generation.

I recently installed the A’PEXi N1 Evo Extreme midpipe on my 2014 IS350 AWD, which deletes the secondary catalytic converters. However, I ran into an issue removing the O2 sensors from the OEM midpipe, and now I’m looking for a solution to prevent a Check Engine Light (CEL) without having to buy new sensors.

I’ve heard of a few possible workarounds (defouler or tune) but I haven’t found much info specifically for the 3rd-gen IS.

 

You just need to get a couple O2 sensor extensions. They are only like $5 each, and they are just a simple spacer that pulls the sensor tip out of the exhaust stream an inch or two so that they don’t read the excess particles in the exhaust stream. You can get them from Amazon or even AutoZone

 

You don't need to buy defoulers unless you add catless headers. Apexi midpipe should not trigger a CEL.