Codes P0134 and P0442

Hello, is this a 2.3Liter engine? There are actually 2 Technical Service Bulletins for this issue, and I believe that your oxygen sensor codes are being caused by the Evap leak that's triggering the P0442. There is a redesigned Fuel cap for this vehicle due to this issue. The fuel cap is leaking air causing the Oxygen sensor to read a lean condition. The front Oxygen sensor on these are not regular oxygen sensors, they are wide band oxygen sensors and are much more sensitive and have a wider range of operation. So, the dealership should replace the fuel cap for free. and you can explain the other codes you're getting to them, I'm sure they are related. The pending code just means that it's happening repeatedly. So, they shouldn't charge you anything. It's a faulty designed fuel cap that is not making contact correctly. If you get it replaced and get other or different codes let us know and we will go from there. But have this taken care of first. I will post any additional information found here.
And just FYI this bulletin is for 2.0liter and 2.3liter

If you did not get a letter in the mail, there is also a Recall on the Power Steering System. This is important to get taken care of right away if you haven't already. It can result in a sudden loss of steering ability. Last 2 pages below

And one more Recall, this applies to a Ground terminal on the Windshield wiper motor may have been bent during assembly and can break. This can cause a loss of wipers, just wanted you to at least know about it. Pages 6 and 7 below.

https://www.2carpros.com/articles/evap-system-code-repair

https://www.2carpros.com/articles/how-an-oxygen-sensor-works

You got a Mazda this time. Usually, you have the European makes. You have Autel scan tools, correct? You can watch the data PID on that front 02 and see what the current flow on it is. I'd be interested to see what the fuel trims are doing at this point too. That would give us an idea if it's a rich or lean condition.

Okay, I'm assuming you got a cap from the dealership. I'm looking at these 2.3Liters and there's two different engines for this model, what Sub-model is this, or if you know which engine is in this vehicle, for Sub-models I've got listed s Grand Touring, s Sport, s Touring and these have the 2.3liter CD L3V engine,
And the other 2.3 is the MazdaSpeed which has a 2.3Liter CD L3 engine. And a Hatchback or Sedan option as well. Or I can go by the Vin # if you have that.
I'm only asking because there seems to be a different code setting criteria for the different engines and sub-models.
For instance, below is some of the differences it is asking me just for that particular code.
These are Direct Injection setups where we'll have up to almost 2000psi fuel pressure, so that's probably why it's asking about different models.
And are you getting a voltage reading (PID) for that Front Oxygen sensor, anything lower than 1.8volts on the Live Data stream? And can you see if there is any Freeze Frame Data for that code?
Go ahead and take a really good look at the connector for the front oxygen sensor. Make sure there's no loose pin fitment or any harness issues there, because it can be reading low voltage for a number of reasons, just want to rule out any open circuit issues, etc, to begin with.

And sorry about all the questions, but is this a California car? The emissions standards are different, and it looks like the actual wiring of the front Oxygen sensor may be different as well.
Hopefully, this is just a bad front 02, but it's odd that the code changed from no activity to low voltage. Did the dealership do any work on this, or did you change the cap?

Was that a fixed reading while the car was running?
And of course, you know this was coming, there's a TSB for this a well. This is for harness damage, because to me a reading of 0.5volts looks like a bias voltage reading, something the ECM would put out on the circuit to check circuit integrity. And if that was a solid/fixed reading, Id say its a bias voltage. It definitely shouldnt be that low, So check the circuit areas in the TSB, ive got the possible causes for both California Emissions and Non Cali. Ill post both for. The wiring is different. Its mostly pointing to a short to ground or open circuit, id think if you had a short to ground it would be even lower than 0.5volts, but that depends on/and if its a short.
California emission are diagram 5&6,
Non-California are 7&8
And I believe even though these are Wide Band Oxygen sensors, there might be a 0-5volt reading on Non OEM scan tools, but I'm not 100% positive on that. It just looks that way with it asking if theres a voltage reading lower and 1.8volts on the California car and less than 1.0 volts on Non Cali emissions. On Wide Band 02s the ECM monitors current flow and not voltage, so it might a change in scan tool data that we're seeing a voltage reading.

So, for some quick tests after you inspect the harness, is try to get some activity out of the 02 sensor. Create a vacuum leak and see if the sensor responds, or try inducing a Rich condition, maybe some propane in the intake, just enough to get the 02 voltage to move if you can. If it doesnt respond at all and the harness is good, At that point Id replace to front 02 and hopefully its not an ECM failure. But an 02 is much less expensive that a computer.

One last thought, check the MAF sensor for any kind of build up, if the MAF is under reporting to the ECM that would cause a lean condition. Thats an easy check, Ill post some other Real Fixes as well.

Okay, that rear 02 voltage 0.5v looks okay, the front 02 (A/F) sensor is going rich with your throttle response, but I would expect that. Have you cleared the codes and taken it for a good few rides? It will need to pass the readiness monitors for the Oxygen sensors and that will take a few drive cycles and certain conditions met. Maybe a cruise on the highway and let it deaccelerate from 50MPH coming off the Highway to a stop. Does that code come back right away? Because the vehicle will need time to relearn a new sensor. That %99 reading is most likely because that Data Pid is not available. So, it puts in a substitute number, The other fuel trims look fine. %5 is fine. If it was hitting %10 or -%10 id be concerned. But erase the code, take it for a couple good rides and see if it comes back. Also, can you get any more Data up on that scan tool?

Yeah, the ECM may just need some time to adjust its fuel strategy. It is always a good practice to erase all codes after a new sensor or even spark plug change. All those things are calculated into the ECMs strategy now. You wouldn't think changing a spark plug makes any difference, but it does these days. Hope it goes well, have a nice day.