Check engine light - 2004 Hyundai Accent

Hi all, hopefully someone can assist me with this issue. My wallet is empty, and I still have this P2096 code mocking me. I initially had the code read at an auto parts store.
I brought my car to a major (corporate) repair place and they replaced the rear o2 sensor. They bragged to me about their expensive, high tech code reader that is “way better then the 60$ one you buy from sears”, and how it can pinpoint my problem exactly. When the check engine light came on 4 days later, I was about to tell them where they could shove their high tech machine, and had my father in law read the code - it was the same one.
I took it back to the repair place and they diagnosed it again (for free as they should!). They now say it’s the front o2 sensor. They would replace it for free and I’d just pay for the part. They wanted to change me over 100% markup on a 65$ part, so my hubby said “no way” and told them to forget it. We bought the part and he put it in. Now 2 days later the engine light is BACK on. Same code.
Now since we repaired it ourselves, the repair shop can now wash their hands of the initial repair and not be held to a warranty. But I still have the same issue, its not fixed and I have no idea where to start the troubleshooting process. What do I look for, listen to, smell, check, etc to start to figure out whey I still get this code? Thanks in advance for anyone’s help!

P2096 Post Catalyst Fuel Trim System Too Lean- Bank 1

Probable Causes:

-Air leak near sensor

-Plugged catalytic converter

-Lean air/fuel ratio

-Faulty sensor

Never believe anyone about their diagnostic computers - if they imply that the computer will tell them what the problem is.

Its also a great idea to avoid major corporate repair chains. Find a good, locally owned, independent shop. They are more likely to be competent and less likely to jerk you around.

P2096 is a Hyundai specific code and as near as I can tell it indicates that the rear O2 sensor is reporting the exhaust too lean. Sometimes this is because the O2 sensor has a problem. But sometimes its just because the sensor is actually doing its job.

Has anyone checked the exhaust system for leaks? Has anyone actually watched the O2 sensors to see what they are actually putting out? You need a new shop where things like this get done before parts get tossed on.

Thanks cigroller! I only used the major repair chain because I have a credit card for them, and it was easier to get it taken care of quickly for no money up front. I guess a “regular” credit card could acomplish the same thing now that I think about it. I will probably write to this repair chain and demand some sort of compensation via an executive email blast. Maybe they will do right by me if I go up the chain. I also intend to look at the rear o2 sensor and make sure it is indeed new.
As far as the issue goes, with two new o2 sensors, I have to assume they are actually doing the job they intended and reporting to the computer what the actual problem is.
How does one “watch” the sensors to see what they are putting out? Is that something anyone can do? I"ll be sure to check the exuast for leaks as you suggested. Someone told me I should be checking for vaccum hose leaks, or the gaskets on the manifold, does that sound correct to you? Thanks again for anyones help. You guys are lifesavers.

You can write to the chain if you wish - and I think some of them might even get a little better if people did provide feedback - but you won’t get any compensation. They probably charged you for diagnostics, a new O2 sensor, and the related labor. That’s what you got from them.

Checking the actual behavior of the O2 sensors requires an automotive scantool - and then a bunch of knowledge and experience to get a read what is going on.

While it could never hurt to look for vacuum leaks I’m not sure that’s the most likely thing for this code. However, I am also perplexed by this code and you will probably need one of the real mechanics on these boards to straighten it out. The reason I am perplexed is that AFIK the post catalytic converter O2 sensor is not normally what the computer monitors for fuel mixture. Its mostly there to make sure that the exhaust gets “cleaned up” by the catalytic converter. The pre-cat sensor should be the primary input for leanness/richness. So its more likely that this code is being triggered by something more on the downstream side (e.g. exhaust leaks, catalytic converter problem) rather than the upstream side (vacuum/manifold leaks). Perhaps this is part of Hyundai’s system for monitoring the catalytic converter.

What year is the car and how many miles are on it? If it is under 8yrs/80,000 miles I might suggest stopping by a hyundai dealer. There is a federal warranty that may cover this if it turns out that your converter is bad.

Ohhh, good to know. I think it might just be under 80k, and its an 04. I will look into this federal warranty as well as checking the exaust system for leaks. Thanks again ciggroller!

Re: djkatscan — 2004 Hyundai Accent — rear O2 sensor

  • an O2 sensor can be tested off-car using a propane torch and a digital voltmeter; google propane testing O2 sensors;
  • DTC P2096 is generic, not manufacturer-specific; the latter have the number '1' in the second location;
  • initially the function of the post-catalytic O2 sensor was to check the catalytic convertor; since about 2000 both the primary and secondary O2 sensors work together to set the A/F trim.