P0037, p0031, p0032,p0131,p0134

NEVER randomly replace parts without first checking to see if they are actually failed.
Check the Monitors and see what emission systems are not in state of readiness this can be a clue to where to look for your problems.

While you did not get a DTC indicating a failing CAT it also may be a consideration to look into.

As well you may have a ECU problem.

But i would recommend NOT to replace any more parts. This often time as you have found does not correct the problem and can add to more problem from the original.

My advice and don't take this personal you do not have the experience and know how to properly diagnose your problem. You do have apparently good DIY in replacing parts so I would get a service shop that has at least a certified ASE Technician to tell you what your problem is and then you can correct it. Otherwise, DIY on forums will likely give you more advise to change more unconfirmed parts. In other words, they will be "guessing"!

BTW you car passed the CA emission testing and was giving the registration for CA. It is NOT "RIGGED" for CA. The CA compliances is stricter than the other states but your year still would have passed the CA requirements and I sincerely doubt any part was added to make is CA compliant. When CA changed the requirements for testing your year was only required to OBDII test not tail pipe. Never the less your Mazda also does not get any allowance in the monitors and all must be in state of readiness. All this was at least from what I recall when I test for my testing certification 2 years ago. I am NOT any longer CA emission certified mainly because I don't work in a shop that offers the CA emission Testing any longer.

@Grendel65 I have tested the O2 sensors. The connectors. I bought first ones and took in for the limited warranty that comes with the parts store. So the second set was replaced for free. And I'm not offended I'm actually happy you are telling me how it is. And I been thinking it might be more than I can handle like you said might be pcm or catalytic converter. When I bought the car they put a different connector on harness to the first O2 sensor I don't know if it should a 4 prong or 5 prong. They spliced a 4 prong on it. But we results say for federal emissions Mazda should be five pin. But the wiring from harness is the same color as it comes up on the California 4 pin connection. And how could I test the monitors with torque pro? Any suggestions. I plan on taking it in to get checked by a pro. Just trying to avoid that if I can but the looking like it's outta my experience and skill set.

Rockjr91 said:

@Grendel65 I have tested the O2 sensors. The connectors. I bought first ones and took in for the limited warranty that comes with the parts store. So the second set was replaced for free. And I'm not offended I'm actually happy you are telling me how it is. And I been thinking it might be more than I can handle like you said might be pcm or catalytic converter. When I bought the car they put a different connector on harness to the first O2 sensor I don't know if it should a 4 prong or 5 prong. They spliced a 4 prong on it. But we results say for federal emissions Mazda should be five pin. But the wiring from harness is the same color as it comes up on the California 4 pin connection. And how could I test the monitors with torque pro? Any suggestions. I plan on taking it in to get checked by a pro. Just trying to avoid that if I can but the looking like it's outta my experience and skill set.

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It very odd that you had a new "set" of Ho2 fail. But if they were really cheap and made in China well we all know about quality of parts from that country. HA!
Your Torque Pro should have a screen access for the missions Monitors. Check for Monitors or system ready in the menu. I don't really care for blue tooth scanning and any and all ECU checking should really be done connection directly to the OBDII Diagnostic connector.
Sorry but it is really hard to compare a 18 dollar diagnostic scanner with a true scanner cost over $1000.00 I use a Snape-on Solis which was closer to 3K. However you might also check the next time you get a DTC before to clear them check for is pending DTC? Pending are the DTC which have not yet cycled enough times and are not actively causing a problem yet but are also not cleared of a problem. Many times cheap scanning device will automatically clear both active DTC(engine check light) and pending also making it troublesome to find the cause of the problem.
As for the HO2 harness not sure what is going on there???? honestly I didn't look. But these sensors are often misunderstood what they are and their proper name. Heat Oxygen Sensor. (HO2) The main difference is 2 wire O2 sensors don't work on the same start up program and are commonly found on pre 2000 engine not OBDII or CANbus from 2002 to present What they incorporate in the sensor is simply a heating element to quickly go form the start up ECU programing to normal engine programing as quickly as possible to improve the emissions during cold start to warm up cycle of the engine. Thats why when you first start the engine it will rev to around 1000-2500 rpm and then quickly drop to normal engine idle speeds. I am telling you this because i am not sure how you tested the HO2 to find them defective? There is more to testing then a simply continuity test. But that's another subject. hahaha!


Recommendation is still to have your ECU checked from someone with experience and a professional Scanner and have them check your monitors. Oh and stop clearing the DTC(check engine light) let the ECU see that you resolved the issue causing them and clear the pending DTC and check engine light. This may take up to 2-4 complete engine cycles

I would be checking for voltage on the heater pins at the O2 sensor connectors. Both sensors share the same power supply for heater circuit, it's a 10A fuse labeled "ENG BAR 3" in the underhood fuse box by the battery so if that fuse goes out then you will end up with a code for both sensors. I would be very suspicious on that spliced on connector, a car with federal emissions DOES only have two sensors and upstream sensor should have 5 pins, not 4. Pull the tape off and see what it looks like. For whatever reason, Mazda stupidly made two of the wires the same color so I'm willing to bet that whoever spliced the connector on connected those wires together, which probably blew the fuse. Get the correct upstream connector, wire it all in, and install the correct sensor. You may have to go to the dealer or junkyard for the connector as I couldn't find a listing for it aftermarket. The rear sensor is also listed as being a different part between federal and CA emission so I would make sure that one is correct as well.

madmatt2024 said:

Make sure you find a true "expert" because as a tech who diagnoses this kind of stuff, I've seen plenty of vehicles that have been tossed from shop to shop without answers. Plenty of techs just throw parts at the issue and give up when that doesn't fix it.

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Couple of things to add. If you are looking for a good diagnostic technician, find a shop that uses ASE Certified Technician and that at least one is currently certified. You will know these shops because it will have the ASE blue sign somewhere it can be seen. These individuals that are current in the last 10-15 years test to get re-certified or certified/ The testing on the diagnostic side of the testing is extensive.
The suggestion would be better to take you Mazda to a Auto Electric service shop because of those pictures of the wiring posted . I say this because a higher majority of service shop won't touch your car because of the wiring changes you or the previous owner did.
I am sure madmatt2024 will concur.... we like his shop turn down many interesting electrical jobs like these done by good intended DIYs.

Grendel65 said:

Couple of things to add. If you are looking for a good diagnostic technician, find a shop that uses ASE Certified Technician and that at least one is currently certified. You will know these shops because it will have the ASE blue sign somewhere it can be seen. These individuals that are current in the last 10-15 years test to get re-certified or certified/ The testing on the diagnostic side of the testing is extensive.
The suggestion would be better to take you Mazda to a Auto Electric service shop because of those pictures of the wiring posted . I say this because a higher majority of service shop won't touch your car because of the wiring changes you or the previous owner did.
I am sure madmatt2024 will concur.... we like his shop turn down many interesting electrical jobs like these done by good intended DIYs.

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Actually, my opinion is pretty much the opposite. We don't typically turn down jobs, let alone one like OP's. If a shop doesn't want to touch a vehicle simply based on OP's wiring pictures, then I wouldn't think very much of that place. Easy money like brakes and oil changes are all they are after. ASE certification also doesn't mean much to me, when you actually take a step back it really looks like a money making scheme. Not to mention, ANYBODY with an ASE cert can call themselves "ASE certified" but that doesn't mean that they are master techs or even have a cert in the area required for the work that needs to be done on your vehicle. Nobody in my shop has current ASE certification, yet we are usually the place that people get sent for diagnostic work when several other shops can't fix the issue. We've even had to clean up after "ASE Certified" techs that did sloppy or incorrect work.

Grendel65 said:

Ok well your going to be one of those that thinks they know because they do and not trained.... LOL
often on forums those that don't have certification post like yours . LOL!
BTW anyone that has an ASE certification generally keeps them hung in plain view for customers to see.

As for your shop taking on a wiring mess like the one pictured in this thread, you would be a rare one and I can see your shop charging a butt load to correct it. That is also why we turn those away the customer may get the issue resolved but always feel like the cost was unfair.

In the end your shop I would say is one that people should be weary of using and who they have working on their vehicles.

Education and training are always better then practicing and learning at the expense of the customer.

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First off, I have to apologize to Rockjr91 for going off topic on this.

I admit, I can be a bit argumentative at night and I'm sorry because I can see now that I really came off that way. But, how can you just laugh and turn you nose up at someone over a piece of paper? That's just sad.

I have to ask: Why would you, a CorkSport employee that (from what I can gather) does ECU tuning , be doing general repair work at CorkSport?
On top of that, this isn't even that big of a "wiring mess". I would rather diag. and fix this than fix CAN bus issues on most cars. If you wouldn't work on it because "the cost was unfair" then do you basically tell the customer to junk the car? It's still probably going to be cheaper to fix this issue than to replace the vehicle. If you're an ASE "master tech" then you should be able to easily figure this out in the standard 1hr diag. time and spend another hour or two to rewire the sensors or source and and replace the harness. You do specialize in Mazdas after all.

I've apprenticed for years to get where I am now, I'm not untrained. Never once did I "learn at the expense of the customer", I learned at the expense of the shop, they openly acknowledged it when they first hired me. This shop pays hourly so at no point are techs under the gun to pump out work for book time or trying to cram 10hr of work into an 8hr shift. If we go overtime due to a tech screwup, we charge book time. Generally, if we go over due to the vehicle condition, we bill extra but If we come in under time, we charge less than book. The shop also supplies all of our tools and boxes. This shop has been in the same family since 1945 and this is just the way they have always done things. I admit, the place I work isn't perfect and neither am I, but to call us a place to be "weary of" without ever meeting us or seeing our workmanship is just plain arrogant.

More off topic banter>
I DO NOT WORK for Cork Sport.

Madmatt as for my comment about being weary about your shop that stands because like you both of us have poor assessment of what is IN THE REAL WORLD regarding member and can only go by what they post. What a couple other members think about my responses and experience on this forum I know the posers which I will say you are not one of them. But there is at least one IMHO on this thread that is. LOL . Needless to say the sheer thought that because I choose a frequently changing signature picture you assumed me to work for a company that I don't and my talents are only EFI/ECI Performance calibrating is a little funny to say the least.

DownerMazda you just summed up the total of your lack of getting training in a school by saying how crazy newer vehicle electronics are. They are a breeze to find and solve electrical issues if you know what to look for .
This OPS wiring is a mess of wires and is not something that shops do contrary to one member that say they would take it on. I am sure their shops insurance would have question if that customers car burned down because of a NONE oem wire repair. You may have read I recommend that the OP go to an Auto Electric shop and not a general service shop for the repair. Maybe you didn't notice the current state of DIY mismatch color wires and poor connections?

Now where is that popcorn eating emocon?? LOL