Got on the highway on the way home tonight and the CEL came on - 2 different codes showing on the code scanner, both P2096.

That means "Post Catalyst Fuel Trim System Too Lean Bank 1".

I searched for "P2096" through this whole forum and there's nothing, which was fairly shocking. Looked elsewhere on the web and only found a couple Mustang references, both to guys with Bama tunes. I have never tuned my engine and it's totally stock, so that's not it. Found some F-150 guys that have run into it and had it be the after-cat O2 sensors.

Any ideas? Before I go about replacing O2 sensors, figured I'd clear the codes and see if it came back or not.

Anybody else run into this? Any ideas? Thanks.

 

Hey Kyle - Sorry to hear about the trouble here but I think the guys over at Bama just need to make a few slight adjustments on your tune here. Can you do me a favor and shoot me a PM with your order info/Email address and I'll make sure that one of their Tuning Specialist reaches out to you today to get you some help.

Alex

 

Thanks Alex, but I don't have a tune - bone stock motor. The only references I could find to that error code online on Mustangs were both related to cars w/ Bama tunes but, again, that's not the case with my car.

 

So using the Ford Service Manual for our cars (http://iihs.net/fsm/?dir=0), here's what I figured out:

Description:
The powertrain control module (PCM) monitors the correction value from downstream heated oxygen sensor (HO2S) as part of the fore-aft oxygen sensor control routine. The test fails when the correction value is greater than a calibrated limit.

Possible Causes:

• Corrosion
• Incorrect connections
• Exhaust leaks
• Contaminated HO2S
  

Diagnostic Aids:
Inspect the connectors for signs of damage, water ingress, or corrosion

Then, going through Ford's diagnostic recommendations from there, there's a ton of electrical testing that is far beyond my capabilities so it seems like I need to just take it to the dealer or replace the bank 1 O2 sensor that's after the cat myself and see if that solves it. Anybody else read this any differently?

 

I wonder if this would be covered under emissions warranty? Saw in another thread you had no issues, must have jinxed yourself .

 

I would doubt it's covered under warranty anymore but yeah, I may have jinxed myself!

Regardless, I found two new rear O2 sensors for $106 shipped from Advance Auto so will put those in this weekend and see if that solves it!

 

Hi Kyle,

sorry for digging out this old thread, but I got exactly the same problem and could not find anything that was not related to a modified engine.
Got a stock Coyote as well and the car threw the same code several times last summer, mostly when outside temperatures were high.
Could replacing the oxygen sensor help solving your issue and has it happened again ever since?

Many thanks
Ben

 

So I don't have a great answer @benshell - The first time it happened back in 2015, if I remember right, it just went away on its own; I didn't end up actually replacing the parts. I had it come up again in 2019, and I did have the left bank downstream sensor replaced, but it came back again not soon after. Then, it went away on its own and has been fine again for months. It's been in storage since November so not sure if it will come up again when I get it out or not.

 

Thanks for the quick answer Kyle.
That's really strange... same here. It went away on its own after storage reset and came back occasionally only on very hot summer days.
Since new and used oxygen sensors are said to have a different voltage level, Ford recommends to change both oxygen sensors at once, I figured it would be good to have a second opinion before investing several hundreds of dollars.
Guess I have to wait till it comes back and then start working on it..

Ben

 

Hey Kyle, long time bud. I have a crazy though. When was the last time you added injector cleaner to your fuel tank? I know your Coyote is pretty up there in miles. My theory is injector(s) are a bit clogged up and don’t deliver enough fuel. This could in theory cause too lean burn. Perhaps.

 

Hey there! Yep, that's definitely a cheap thing I should do when I get her out of storage. I know I've never paid for the dealer to do a fuel injection cleaning, as that's always seemed like one of those unnecessary add-on sales but I could be wrong!

 

Hi, Now that my car's out of storage I can confirm that the issue still existed ;-)

I used an OBDII reader and found out that the downstream sensor voltage was way too low.

Replaced both downstream sensors and the code is gone.

Cheers Ben

 

I just got my first mustang yesterday, 2014 GT Premium
I just started to have this same issue with the P2096 code, the only things that have been done to the car has been a K&N cold air intake, and a Corsa Catback exhaust, neither of which I did and there is no tune on the car. Im pretty concerned and annoyed about this considering I've had the car for less than 24 hours. I haven't beat on the car, maybe a total of 3 pulls, I've heard that a cause could also be an exhaust leak, considering the aftermarket exhaust I think this may have something to do with it. I just wanna make sure I didn't do anything to cause this code.

 

Welcome and congrats on your first Mustang! I would say the chances you did anything to cause it are almost non-existent. The consensus seems to be it comes/goes somewhat randomly and the cheapest/easiest solution is either waiting for it to go away or replacing the two downstream O2 sensors. Not sure how tough a job that is, as I didn't do it myself.

 

Thank you! This just sucks because the car is so new to me, I cleared the code and drove it for a bit and it seemed to go away, but as soon as I get on it at all even going to like 4500k at like half throttle it throws the check engine light.
Ive been trying to keep the A/F Mixture gauge up on cluster but the numbers are kinda vague to me.
Car only has 55,200 miles on it too, I can try and get it up on a lift this weekend and check the voltages of the sensors. Is this something I can still drive with or can it mess more stuff up if I do?

 

In my experience, the car didn't drive any different with or without the light on so I would think you're fine. Those sensors aren't that cheap (looks like $58 each on RockAuto for the Motorcraft ones) but if you're getting under the car anyway, you might just replace them vs. chasing the issue for a while.