O2 Sensor issues P2096, error codes not disappearing

Have had this problem for some time, and my previous mechanics tried everything to fix it. Finally thought i would give Mazda a try again. I only ended up using them for the 1st 3 years, as they constantly let me down, charging for things they didnt do. Anyway, I gave Mazda a go. They said they knew what the issue was and changed 1 sensor, but the issue returned. I asked them why they didnt change the 2nd sensor, and they said they typically didnt change both. Then they changed the second one, not cheap here in Australia.
I have the same issue. It appears they did no diagnostics, just assumed. Now they are talking about injectors, getting them tested and replaced. $585 each here.
I need some thoughts on how I should approach this. I would appreciate some advice.
It doesn't sound like you're a DIYer, so what type of advice are you looking for?
Just thoughts. What sort of things might be causing this, as in components, and what I should be asking Mazda to do. As noted, they jsut changed stuff without and disgnosis as far as I was concerned. I run a small IT consultancy, and I disagnose issues, I dont start changing parts and see what happens. Again, as I mentioned, they are talking about the Injectors. I dont see how the injectors have anything to do with the sensors. I will be talking to them tomorrow (mazda) and actually lodging a compliant to Mazda about it (They didnt even show me the parts they took out and proved something was wrong.) As they are actually Mazda, I can complain to their HO. Also, I will be talking to another mechanic I know. I was promised changing the O2 sensors would fix the issue, it did not.
As for the advice, I mean anything. What would anyone do with the same issue, where would they start. I go to forums in IT to get ideas and info, and I am always grateful to people's opinions, etc, and most of the time, people's thoughts and ideas are in-valuable. I am hoping the community here is the same. If I dont know, i want to find people who have experienced the same sort of stuff and dealt with it, in particularly, the P2096 error.
Last edited:
For anyone who is not hands-on with your vehicle, it's nothing but guesswork. For me, problems with multiple possible root causes are all about diagnostic testing, and that's always what I do first. Other sources might say it's this or that, but IMO it would be a complete waste of your time to present any third-party suggestions to a shop. They've heard it all before from the internet experts, and will just roll their eyes and ignore it. And frankly, I'd probably do the same thing myself.

But I certainly do feel your pain - actually anyone who is dependent on someone else to do work for them. It sounds like you've already been to multiple shops, and it's appalling to me that no one seems to be able to work through what should be a straightforward problem. The only thing I'll say for sure is that I'd never start flinging expensive injectors at this problem, unless there's diagnostic test evidence which supports that course of action. I hope you find someone who can figure this out, before your wallet gets completely cleaned out:rolleyes:
I understand what you are saying, but I still want to personally have an idea of what I should be looking for, and I would appreciate your help. I dont care if people roll their eyes. I come to forums to get ideas. Where would you start? you also have to understand its Mazda that are giving me this run-around, so I need information from other people to assist me. Why is this so hard on these forums to get help? Poeple have options and have ideas of where to start with stuff. People in IT help each other, and dont care about rolling eyes.
Last edited:
.... Where would you start? ...
If this were a problem with my vehicle, I would start by: testing the health of the charging system; evaluating the freeze frame data associated with the code; check for possible additional pending codes; monitor OBD live data with the vehicle running; and clear the code to find out how long it takes to be reset. After doing all of that, I'd move on to the next phase of diagnostic testing, hopefully based on what the results of the previous testing has shown.
thanks very much.. Mazda will do nothing like this, the next step for them is look at the injectors as I said. They say it is probably one injector... the "probably" is what I dont like... although, they did agree that I dont need to pay the labor component, and just the cost of cleaning the injectors if required. I told them they get one more chance. I am waiting on another mechanic to get back to me.
I dont care what they think, but i will be discussing your thoughts on this. Thanks.
For one, what year car is this? What engine? What transmission?

P2096 - Post Catalyst Fuel Trim System Too Lean Bank 1

Since the sensors were replaced...or at least I hope they were, then it's an actual LEAN problem. Too much AIR and not enough FUEL.

You need to have a shop diagnose it. It could be several issues. Weak fuel pump. Vacuum leak allowing in air. Mass Air Flow sensor going bad. Throttle body issue.

Usually it's not an injector issue. Any shop that is going straight to the parts cannon before KNOWING what the problem is are CROOKS.
I know this trail is a little bit old and for a different model; but I am curious about the resolution here because I recently encountered the same P2096 code (current, pending and permanent) on my son's 2011 CX-7 2.3L Turbo which is preventing Emissions Inspection. Inspection shop wanted $150 to just "diagnose the possible cause."

For us, there was a 2012 TSB repair/reprogramming for the P2096 code which was done on the car years before we bought it used - https://static.nhtsa.gov/odi/tsbs/2012/SB-10097947-2532.pdf. So I walked through many of the steps mentioned above and elsewhere: inspected the manifold and exhaust system for cracks/leaks; inspected the engine air filter, air box and hoses for dirt, clogs, cracks, leaks; inspected the throttle body; inspected the air hoses to the intercooler and the intercooler itself; ran/reviewed the freeze frame data and live stream data for the upstream and downstream O sensors, the MAF, and the fuel trims, etc.; cleared the current and pending codes with my scan tool (permanent code wouldn't clear) - current and pending codes returned within a few miles of driving; cleared the codes again and then disconnected the battery terminals and then touched the leads together to try to discharge the capacitors and clear the permanent code, and then reconnected and let engine idle to hopefully reset programming on the PCM to current engine conditions (didn't clear the permanent codes); cleaned the O sensor harnesses and the MAF harness and the MAF itself (no change); replaced the MAF (no change in performance or freeze frame/live stream data). Codes still kicked.

And then, something said 'double check the air filter itself' - and I did but this time I also checked to confirm it was the right filter. Lo and behold, 3 self-performed oil changes ago (curiously right about when my son first notice the code started kicking) AutoZone pulled the wrong air filter off the shelf for my son - gave him a CX-9 filter rather than a CX-7 air filter - and he put it in. Lesson learned!!!. The two filters are different enough in size and shape (rounded edges versus squared edges) to cause the air box to fit imperfectly and allow extra air in. With the new proper filter in, the codes didn't kick again - not even after 10-15 miles of driving.

And, I replaced the spark plugs for good measure with the upgraded NGK Ruthenium HX plugs that I had bought when I though the plugs might be the issue. The removed plugs were OEM but not sure if they were the original plugs. So, replacing them made sense anyway - this was "fun" as I had to remove the intercooler to get to them (and the air box to easily remove the intercooler) and of course I lost one of the nuts in the engine bay black hole . . . never to be located again. WTH are engine bays like the Bermuda Triangle for nuts, bolts, screws and washers???

Anyway, I test drove her for about 10 miles - all good; and then my son drove her for about 30 more miles yesterday (highway and city) - all good. There are no current or pending codes; and the permanent code cleared as well.

My time aside, I'm in for $12 for MAF cleaner, $20 for new air filter, $50 for new plugs and $0.20 for an extra nut and lock washer - I'm returning the new MAF and O sensors.

Hopefully our P2096 mystery is solved and we can get this thing inspected and back on the road! And hopefully this helps any other Mazda owner with the dreaded, zombie-like P2096.