Flashing check engine light upon hard acceleration. P2096 only code: "Post cat fuel trim sys too lean bank 1"

[hawkman71]

Hi y'all. I did a search on this forum for "P2096" as well as the full message in the thread title (post catalyst system too lean bank 1) and haven't found what I need.

I have a 2011 Exped with only 150k on it that has given us its fair share of problems over the years. However, when it runs, it runs great. My wife has said the check engine light has been on and off lately. Then, she called me after passing someone on the road. She said "when I accelerated to pass this person, the check engine light came on". At first I thought, ok, not too big a deal, but then she said it was flashing when it came on. After passing and resuming regular driving, presumably around 60-62 given a 55mph speed limit, she said the light went off again.

I took it too a Advance Auto and their unit showed 3 instances of the same code: P2096 Post Catalyst Fuel Trim System Too Lean Bank 1.

I don't drive this vehicle a lot. My wife does and mostly for short trips. School, church, and her mom are within 1.5 miles down the same road. Town is 25 miles away. When I drove it yesterday, I thought 'yeah, this vehicle feels heavy, perhaps it's running quite right, feels sluggish'. But I can't tell that the engine is necessarily running bad.

*Note: our AC compressor went out for the 3rd time in 2 years - just after the warranty on the last repair expired. I'm not fixing it. I pulled the fuse and the comp is free-wheeling right now. Shouldn't be a part of this issue. If you have a warning for me about driving it like this - please let me know. The idea is to trade the car in.

I thought that b/c it flashed, it indicated a cylinder misfire and that urgent repair was needed.

Anyone else experience this? Any ideas? What I've read elsewhere is that it could be a number of things.

We're leaving on a family trip next wednesday (these things ALWAYS happen a week before these trips) and the Ford dealership is booked until after Christmas, though I could talk to the owner who has helped me before - I just don't to wear out a welcome, seeing as I'm not a new-vehicle buyer due to finances, iykwim.

I can try some local guys that are reputable.

I'm curious if a better diagnositc tool will find more codes or tell more about the issue. Can I rely on a small-town repair guy to just know the exact issue?

 

[Trainmaster]

Sounds like you had a miss. The spark was failing which set a lean code.

Don't pay any attention to anything Advance Auto tells you.

A professional Ford-enabled code reader, used with proper diagnostics, will detect and identify any miss that's happening. When were the plugs last changed? If it's been more than 80K miles, I'd start there.

 

[Timo2824]

If your compressor is failing that often you need to find another mechanic...

 

[hawkman71]

Sounds like you had a miss. The spark was failing which set a lean code.

Don't pay any attention to anything Advance Auto tells you.

A professional Ford-enabled code reader, used with proper diagnostics, will detect and identify any miss that's happening. When were the plugs last changed? If it's been more than 80K miles, I'd start there.

I appreciate it. I'm going to check with another Ford dealer and see if he can at least look at it.

If your compressor is failing that often you need to find another mechanic...

Well, Ford dealer. (But you may be right.) Replaced everything, lines and everything. Loaned me 3 new navigators over three months last summer. I think it's shoddy rebuilt compressor.

 

[NorthGeorgia]

"...........had a miss" would be the best answer. I had this happen a couple of weeks past. In Atlanta, I attempted to pass someone. Admittedly I 'stomped' the gas peddle and I didn't think I was accelerating.....made the mistake of 'stomping' it again. I keep foregeting about 'turbo lag' anyway the 'check light' came on and the engine sputtered. And it too did not stay on but 'flashing'. After a few moments of calm, so to speak, the light went off and the engine ran smoothly. A Master Tech put his 'computer thing' on the vehicle and that is what was registered......... a misfire. I am assuming my stupid double stomp caused it. Vehicle is running fine ever since.

 

[hawkman71]

n were the plugs last changed? If it's been more than 80K miles, I'd start there.

I don't mind looking stupid as long as I learn from it each time. When you asked this question, it struck me that they had not necessarily been changed when we got it at 93k. At 150k now, it was time to do so. I thought it had been running ragged lately...

... Fast forward a few hours, (including time to buy a 9/16 plug socket!), and the thing is purring!


*Note: I watched a YouTube video to make sure there'd be no surprises and that it was something I'd be able to handle. It seems simple enough and the guy mentioned using a 5/8 socket. Imagine my surprise when I put a 5/8 socket down the hole and couldn't get a grip on a plug! I took a new plug out of the box and saw that it was a 9/16. I've never come across that before and didn't know that was an option. My last socket set only came with a 5/8 and 3/4 socket. I went in the house and looked at a few more YouTube videos and some internet searches and found everyone saying 5/8...

Call the parts store to make sure they had a smaller socket and they did. Perfect.

Thank you to you and everyone else for their suggestions.

 

[studabaker]

Lean or rich refers to fuel concentration. If you smell fuel from the exhaust then it is not burning or excess is being injected... a lean code would suggest that fuel is not being injected. A flashing engine is of concern if it goes away then the failure has stopped. The flashing engine should be stored and read by an app like torque. I like that one for my phone with a 15 dollar obd Bluetooth elmscan from Amazon. I have also started using forscan on my computer to monitor the graph that can be recorded while driving. This program along with a USB obd to my computer will allow you to make the failure occur and look for faults at that time.

A misfire (to me ) is no spark which would lead to a rich condition if your injector continues to do its thing. This can be monitored by graphing the specific o2 sensor and comparing those values to the other o2 sensors. It will give numbers and if one is greater than the others that one is rich. Common sense would say the upstream should also be rich but the exhaust splits (2nd gen anyway) and this could lead to an upstream low and downstream rich... there should be bank 1 and 2 and down stream o2 sensor. So right left and after the cats. Might even be 4 I'm not sure.

I would also like to say that anyone who knows stuff learned it at some point and did not know it before that and so verify my comments as well because different gen also but lean vs rich is the same and o2 sensors are all the same..