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Discussion Starter · #1 ·
The dealership wants to charge me $380.00 for an O2 sensor replacement if it's not covered under warranty. I'm not sure which O2 sensor it is but is this a reasonable price quote?

If anyone has part number information for the O2 sensors could you please hook me up? All I've found is the O2 sensor wrench tool number (SST 49-L018-001).

The workshop manual procedure to replace this part doesn't look difficult. Has anyone had to replace an O2 sensor before? What were your experiences?
 

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Can you give us some background? Why the need for the new o2? Have you done exhaust work to your car?

A local guy had to replace his o2 as it striped during a header install. Mazda called it an "air to something or other" and yes, it was around $380. :shock:
 

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Discussion Starter · #4 ·
I have a CEL and need to pass emissions. I have not done any work to the exhaust. Stock intake as well and nothing has been done to the engine.

Mazda said it should be covered under warranty unless they find a reason it shouldn't be. My car is lowered and they said I may have hit something that caused physical damage to the sensor. They were unable to get my car on the rack today to determine if it was physical damage though.

If I could find part information or specifications on the O2 sensor to purchase another one I would be willing to do the replacement myself. Anyone know where I could get this information?
 

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Yikes. Well, having worked on several headers and exhausts, I can say they o2 sensors are pretty hard to access to damage. I highly doubt they can prove your lowered suspension is to blame.

I would persue the warranty work. Good luck with the replacement.
 

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Discussion Starter · #6 ·
Yeah I'm with you and doubt it's physical damage because the front end of my car is still intact. The only thing I can think of is that it simply malfunctioned or malfunctioned due to the cold winter we've had here in Wisconsin.

Thanks for the replies.
 

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Yeah, if you haven't done any exhaust modifications it sounds like it should be covered under warranty.

Here is a diagram of the different options for the 2006 exhaust system. Unless your car has California emissions, the first diagram is probably the correct one:



Per this diagram, depending on which sensor went bad you need either D-code 18-707 or 18-861B. MSRP on them are $223.12 and $171.64, respectively.

The first sensor is very straightforward, but there are over 10 different matching sensors for the second sensor's D-code, and I honestly have no idea what the differences are... so make sure you talk to Mazda before ordering one yourself if you go that route.
 

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Discussion Starter · #8 ·
I do have California emissions unfortunately. Those diagrams are really helpful and so is the part/price info. Do you know what the difference between the first California diagram and the second one is?
 

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Discussion Starter · #10 ·
Mazda replaced the O2 sensor under warranty, however, the CEL did not go away.

Their paperwork has a system diagnostic code of P0043. I can't find this code using the table from http://www.fmvperformance.com/fmvarticles/index.php/Mazda3_Check_Engine_Light_Codes. The only thread on the forums I can find states "my CEL code is P0043 - Heater Circuit Low. Was told it is the 3rd O2 sensor...". Does anyone know what code P0043 is?

The dealership had to call Mazda HQ or something to ask why I'm still receiving this problem and they said it may be the result of a loose pin connection somewhere from vibrations but when I asked where or which connector or what could be vibrating or what is causing the vibration they couldn't tell me. All they said was that it wouldn't take them long to check this problem. Does anyone have a clue on this? This seems really strange to me.
 

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Our car uses heated oxygen sensors, that code means that the heater isn't getting enough juice to heat up the sensor properly. If they replaced the sensor, then that does point to a wiring issue. Should still be fixed under warranty, and they should know how to check all the pins for the proper voltage to track down which one has a bad connection somewhere.
 

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Discussion Starter · #12 ·
So it would be the O2 sensor connector... Is this a check I could easily do myself or should I let the dealership finish what they started?

Is there a reason that the CEL disappears after resetting the ECU but then the second time the car is started up again the CEL comes back?
 

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Discussion Starter · #13 ·
Update:

Mazda checked the suspected faulty O2 sensor connector and stated the pins are fine. When they said fine I took this to mean there is no physical damage (bent, broken, etc) to the pin. They also stated that they are not able to accurately determine the voltage for the O2 sensor because I have a battery other than stock, did the Big 3 upgrade, and have 0 gauge running to the trunk to power my amp/sub. Until I put the stock battery back in and remove all wiring they will not look at my car any further.

The service desk lady stated the problem is easily fixed if one has the knowledge and time or they can fix the problem for $988 (without tax) but they can't tell me what to fix or where to begin looking for the problem. This information came from Mazda HQ because the tech at this dealership didn't know what to do.

When I installed a higher capacity battery I had to modify the stock harness that connects to the positive terminal of the battery so that it would fit the battery I put in the car (Diehard Platinum). All of the original wiring is still in place. I kept the goofy looking connector piece that attached to the positive terminal that is on all Mazda 3's because I read that some people had issues starting their cars without it. I did not alter the connecting harness other than grinding down some of the metal so my battery terminal connector could fit on top of it. It isn't exactly the best looking setup but it is efficient and works. I can take pictures if needed.

My car has PZEV California emissions. I have three O2 sensors. Only one of them is popping a CEL code. If this truly is a voltage issue caused by my battery and my additional wiring (keep in mind the stock wiring is still there, as ugly as it is), why am I not receiving errors for the other two O2 sensors or for any other electronic device within the car?

If the problem does involve a difference of potential for the O2 sensor, why does this one not have any voltage regulation at any point along the input path to the sensor? This is probably more of an engineering question than related to my specific issue...

Does anyone have any information about what voltage ranges I should be seeing at the O2 sensor connector pins? I have the workshop manual and have no problem investigating this myself this upcoming weekend. Anything at all involving voltage/current levels at specific points within the car would be greatly appreciated as well.
 

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Depending on which O2 sensor you're looking at, you'll see different behaviors. For narrowband sensors, the voltage should bounce relatively often between ~0.1v - 1.0v.

On my own car (a 2005) there are only two narrowband 1v O2 sensors; the wider-range sensor was not introduced until 06 (so your car most likely has one). So, I'm not sure of the typical operating range and behavior of that newer style 5v sensor during normal operation.

I can say though, that I've got quite a bit of stereo equipment installed too, as well as an aftermarket battery, and it doesn't seem to affect those sensors. I've not done the big-3 though.
 

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Discussion Starter · #15 ·
The copy of the workshop manual I have (I think it's older) does not have anything for DTC P0048 but looking at DTC P0038 (Rear HO2S heater circuit high input) looks like a similar procedure. I am assuming P0048 is for the third O2 sensor on California cars. Correct me if wrong.

My workshop manual has two procedures for P0038 (LF or ZJ, Z6). I don't know which one I am to use because I don't know what these codes mean but the steps are similar. The step states:

"NSPECT REAR HO2S HEATER CONTROL CIRCUIT FOR SHORT TO POWER SUPPLY
• Turn the ignition switch to the ON position (Engine off).
• Measure the voltage between rear HO2S terminal D (wiring harness-side) and body ground.
• Is the voltage B+?"

What is "voltage B+"? Is this a reading I should see on a special Mazda testing tool?
 

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i have 1 primary and secondary o2 sensor laying in my room doing nothing. Both work fine. I changed them thinking it was the o2 sensors but i still get the p0410 code so i don't know what else it is. First i got the code that the primary o2 is faulty and now i got the code that there is no o2. Car feels slugish too. All this started ever since i wrapped my header.....Gas mileage is also reduced a long with power....
 

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Discussion Starter · #17 ·
I found this in the workshop manual for LF (I don't know if that's what I have or not, see above post):

Rear HO2S voltage
Engine condition
Voltage (V) Accelerated: 0.5-1.0
Voltage (V) Decelerated: 0-0.5


I'm going to try and recreate the stock wiring system as much as possible this afternoon.

cali_axela I appreciate your help and ideas. Since you have additional wiring and an aftermarket battery but have not done the Big3 could you take a few pictures of your battery/harness setup? Those would be extremely helpful to me to help recreate stock setup.
 

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Discussion Starter · #18 ·
SOLVED:

For those of you experiencing a P0048 CEL code I suggest you inspect your engine bay's fuse box. Another member here who had a P0048 code had their angel eyes power wire tapping into the fuse box, which is how the guide on the forums for installing the angel eyes instructs you to power them.

I have angel eyes but they are wired through a switch I installed in the center cup holder to the battery. The manual shows two fuses for O2 sensors (#31 and #32 I believe). For those of us with three O2 sensors I am not sure how this is wired or if there is an additional fuse for the third O2 sensor because the manual seems to be for every state that doesn't require the third O2 sensor (CA, etc.). Check these two fuses. Mine were not blown but there was a decent amount of debris in the fuse box so I removed most of the fuses and thoroughly cleaned the inside of the box and the terminals.

The CEL was on after starting the car after this procedure but the second drive cycle cleared the code (some say it can be 3 drive cycles and Mazda could not tell me exactly what the conditions for clearing the code would be but I know I saw it in the workshop manual somewhere).

If you have angel eyes and are using the fuse box to supply power to them, rewire your angel eyes using an appropriate connector and connect it to the battery through a switch and reset your ECU if need be. If you don't have angel eyes, check the fuses and the fuse box for cleanliness.
 

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it must feel good to save some bucks :p
 
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