Originally Posted by TMessick
First off (and in general for anyone looking for help) please post your mods! Quite difficult (and a lot of guessing) if we don't know the hardware you're dealing with.
Highly reccomend finding someone with a Tactrix cable (or getting one yourself) and getting some logs. Uncle Scotty's kind of got the method to the madness of diagnosis (follow the SM).
In a generic sense, DS fuel trim lean (P2096) means that the control system couldn't get the downstream sensor down to the voltage it wanted, so the system is out of control. As such, you get a fault. COuld be a problem with the DS sensor reading incorrectly high (sensor/wiring problem, sensor out of exh stream) or a tune/HW issue where you're running a bit richer than the cal is set up for and the DS control is trying to pull out fuel to get you back to "normal" but runs out of authority.
Possible causes in order of SM diagnostic procedure) are:
2) rear O2 sensor reading stuck hi or offset (failed sensor or wiring, should be able to see it on logs)
3) rear O2 sensor offset hi/biased (failed sensor or wiring, should be able to see it on logs)
4) rear O2 sensor wiring failed between ECU and sensor signal (fix wiring)
5) rear O2 sensor signal reference offset (failed sensor, replace)
6) air leak in the exhaust near the front O2 or rear O2 is isolated (repair exhaust)
7) ??? not sure how an air leak would cause this, but a borked MAF might
8) high fuel pressure causing rich event
9) failed pressure regulator (see above)
... (I'm too lazy to check these, they are unlikely)
I'd say an aftermarket exhaust by itself is unlikely to cause this, but any of the various "CEL" fixes applied to the DS O2 _could_ be causing it.....
well i did just get a new TXS exhaust and i had to extend my o2 sensor wiring by about 5" to reach the o2 bung in the new exhaust. im hoping i have a loose wiring connection in there. makes sense. i didnt get this code until after i did the o2. it was about 4 weeks ago. i got the 1st cel a week ago
sorry, my mods are FP Green 50 Trim Turbo, Perrin FMIC, SMC meth kit, Perrin BIG MAF intake, Perrin 816cc modded injectors, Perrin Radiator Reservior, Tial Bov, Walbro Fuel Pump, Turbo XS 4" downpipe, Turbo XS racepipe, Turbo XS exhaust, Thermotec turbo wrap, Thermo-tec Cool Tube on I/C Pipe, Custom turbo heatshield, Heatwrapped downpipe, GFB Red pulley kit, Carbon Fiber radiator shroud, NGK Iridium colder plugs, Motul Race Oil, STi high pressure radiator cap, Apex-I AVC-R, Apex-I TT, HKS TT harness, Ecutek ecu custom street tune by Scott Siegel, monitored by Ecutuk Delta Dash Software.