Hello, I have a 2005 350z touring non Revup. I keep getting the annoying P1273 code (Air/Fuel Ratio sensor 1)

The mods are:
Megan test pipes
Kenetix V+
Stock intake tube with stillen intake filter after MAF
Catback exhaust with no leaks

The car is not tuned

I have been searching through different threads and most people say test pipes and bad MAF can cause the code to come up. I went ahead and replaced the MAF sensor and installed high flow cats. The code came back after about 30 miles of driving, It typically comes on in traffic or little to spead. Should I replace the B1 S1 O2 sensor? What else may cause this code that I should look for?

My inspection expired 7 months ago and I really would like to avoid a ticket.

 

A little update. I swapped my test pipes out for a set of old high flow cats and this is the result after driving
P2173 (A/F ratio)
P0159 (o2 slow response B2S2)
P1166 (Heated o2 S2)
P1167 (Heated o2 S2)

I recently replaced the B2S2 o2 sensor about 100 Miles ago.

 

I have a feeling it has something to do with the intake manifold design. The code suggests one bank is running a little too lean. This would make sense if one bank of the intake runners in the front of the engine was hampered more than the other side.


Being this is a common error code that occurs when we start modifying the engine, I'm thinking the engine intake is the cause. If you've seen the front of the intake, you'll notice that the volume of air available up front is definitely lower than towards the rear. With that in mind, its possible the furthest most cylinder runner is getting a substantially smaller amount of air than the second, and so on.


But that's just my guess. I've chased that code like crazy to no avail.

 

I am lightly modded as well and tuned. I have gotton that code(and others related) twice now. 1st time it came on during the highway going 75mph. The 2nd was when I had to use 92 gas; however when i filled my tank later with 93 the code went away. The tune however pretty much solved all the code problems. I started having the exact problem as you with just intake ,testpipes and a catback.