CEL Code P2096 w/ exhaust only

[ShutterSpeed]

I was cruising along at 75mph today when I felt the rpm's drop and noticed a check engine light. The cruise control light glows amber now and I cannot use cruise control now.

Got the CEL Code read at Auto Zone and it came out to P2096; Post Catalytic Fuel Trim Bank 1 System Too Lean.

Now I've read that this could be a number of things:
-Exhaust Leak
-High Pressure Fuel Pump
-MAF Sensor
-Failed O2 Sensor
-Leaking Fuel Injector or Fuel Pressure Regulator

Weird thing is that the car runs fine and there is no sign of fuel cutting out or RPM's dropping off or anything similar to that. Car feels fine and no issues.

So my question is have any of you experienced this problem or know of a direction I should start to try and eliminate this code and the car back on even playing field.


All I have done to the car is the Tomei 60R exhaust and a Cosworth air filter. The main thing I believe it is, is an exhaust leak at the catback to front pipe connection from when I installed the exhaust. But any help is appreciated.

[F1point4]

This P2096 code is thrown by the rear O2 sensor IIRC. I talked to a tuner and he said the code is usually thrown if your fuel trims (short and long term) are outside +/- 10. He said its more of a nuisance code than anything and the car should run fine. When the car thinks you are lean, it'll throw in more fuel to compensate so you will actually be running rich. Too Rich or Lean is bad, but Rich is always better and safer.


Since you are NA with light mods and untuned, why you are getting it perplexes me. You would need to have an exhaust leak around the rear O2 sensor for it to read lean. Your Tomei is just a catback so its way downstream of your O2 sensors, so a leak down there wouldn't affect your readings at all.


I've been getting the code as well; after reading your post, i'm far more modded than you. (Vortech, full exhaust)

I have never got the code until the weather started changing drastically. I'm not sure if you guys in NOLA are seeing 20-30 degree swings in temperatures like every other day but it has been like that the past 2 weeks here in Houston. I'll reset the ECU and the car runs fine and doesn't throw a code, then when the weather changes, boom, code thrown.


I'd try the following
+Fix the leak in your catback, probably should get it fixed regardless
+Pull your MAF sensor (it's on the airbox) and make sure its clean and not oily
+Take out your rear O2 sensor (not fun while attached to the car) and make sure its not fouled up.
+Check all your intake plumbing for leaks/cracks. Cracks in the intake hose could allow air to be sucked in after the MAF sensor takes a reading, which would actually make your car run lean.


I'm going to talk to my tuner and figure out what is going on with my car. I'll report back if I find anything. Hope that helps

[ShutterSpeed]

Thanks for that reply man. We actually have been having incredibly random weather. 30 at night but 70 during the day and then back to 60s the next day. Wacky stuff.


I'm gonna check the exhaust tomorrow and probably pull the maf and clean it regardless. Ive read also that if the air filter is dirty it coul cause this and so could fuel contamination. So I'm hoping I can fix an exhaust leak and be on my way.

[ShutterSpeed]

Originally Posted by F1point4

This P2096 code is thrown by the rear O2 sensor IIRC. I talked to a tuner and he said the code is usually thrown if your fuel trims (short and long term) are outside +/- 10. He said its more of a nuisance code than anything and the car should run fine. When the car thinks you are lean, it'll throw in more fuel to compensate so you will actually be running rich. Too Rich or Lean is bad, but Rich is always better and safer.


Since you are NA with light mods and untuned, why you are getting it perplexes me. You would need to have an exhaust leak around the rear O2 sensor for it to read lean. Your Tomei is just a catback so its way downstream of your O2 sensors, so a leak down there wouldn't affect your readings at all.


I've been getting the code as well; after reading your post, i'm far more modded than you. (Vortech, full exhaust)

I have never got the code until the weather started changing drastically. I'm not sure if you guys in NOLA are seeing 20-30 degree swings in temperatures like every other day but it has been like that the past 2 weeks here in Houston. I'll reset the ECU and the car runs fine and doesn't throw a code, then when the weather changes, boom, code thrown.


I'd try the following
+Fix the leak in your catback, probably should get it fixed regardless
+Pull your MAF sensor (it's on the airbox) and make sure its clean and not oily
+Take out your rear O2 sensor (not fun while attached to the car) and make sure its not fouled up.
+Check all your intake plumbing for leaks/cracks. Cracks in the intake hose could allow air to be sucked in after the MAF sensor takes a reading, which would actually make your car run lean.


I'm going to talk to my tuner and figure out what is going on with my car. I'll report back if I find anything. Hope that helps

random off topic question. you going to wekfest tx on the 15th? ill be out in houston with some buddies from nola and baton rouge who are showing there.

[F1point4]

Originally Posted by ShutterSpeed

random off topic question. you going to wekfest tx on the 15th? ill be out in houston with some buddies from nola and baton rouge who are showing there.

yeah I plan to be at the pre-Wekfest meet the evening of the 14th. I'm not showing though.

Let me know if you will be there that evening.

[CSG Mike]

Ironically, I JUST experienced this in a car I was guest driving other FRS/BRZs this weekend.

We do not know WHY the code was caused, but it has not yet come back. If it does, I'll update.

[ShutterSpeed]

Originally Posted by CSG Mike

Ironically, I JUST experienced this in a car I was guest driving other FRS/BRZs this weekend.

We do not know WHY the code was caused, but it has not yet come back. If it does, I'll update.

Yeah I checked the MAF Sensor, air filter, and for an exhaust leak but nothing going for any of these. I reset the ECU and will also update this thread if it does.

I'm really confused why it came about considering I've put about 2-3K miles on this exhaust already. Cant forsee it taking the car that long to determine whether the car is running too lean.

[ShutterSpeed]

Originally Posted by F1point4

yeah I plan to be at the pre-Wekfest meet the evening of the 14th. I'm not showing though.

Let me know if you will be there that evening.

Yes I will be at the pre-meet that evening, driving up there that morning. Should be showing up with all the Low-Weezy-Ana people.