Difficulty

Moderate

Steps

3

Time Required

                          4 hours

Sections

1

  • Oxygen Sensor
  • 3 steps

Flags

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Introduction

As the device was fairly new, I susptected it was something else. Clearing the fault code while the engine was warm, seemed to work, so I suspected the built-in heat element was not working. However the fuse #37 was OK (see https://www.autogenius.info/mazda-5-2007…)

I then removed the sensor and cleaned it using ultrasound (and gazonline), but that did not solve the problem.

In disbelief I went on and checkes all (!) the relays, but they alle seemed OK

Finally I decided to order a new sensor from a webshop (somehow all webshops I found seem to share the same Berlin address…). This is the part I ordered: https://www.motordoctor.dk/products/8126…

Before mounting the new sensor, I did a non-scientific check of the pins (see the steps below) and the results are listed in this table:

As you can see from the table above, there clearly is a difference in the behaviour of the new and the old device.

I installed the new device and followed the instructions:

  • clear the error codesdisconnect the car battery for som minutestake the car for a 10 minute drive

After this, the problem was gone.

What you need

Step 1

              Fuse box check
  • Check the fuse for the pre-heating of the oxygen sensor (in this case #37)

Check the fuse for the pre-heating of the oxygen sensor (in this case #37)

1024

Step 2

              Enummerate pins
  • Unplug the sensor and decide on a numbering scheme. Also clean the pins to ensure this is not a connection problem

Unplug the sensor and decide on a numbering scheme. Also clean the pins to ensure this is not a connection problem

Step 3

              Meassure
  • Check all combinations of the pins of problematic sensor. See comparison chart above (with the new replacement sensor).
  • If you do not have such a tester, a normal multimeter (resistance and capacitance) should be sufficient
  • If you would like a transistor tester, you can search Aliexpress for one. It is an amasing little device. https://www.aliexpress.com/item/10050015…

Check all combinations of the pins of problematic sensor. See comparison chart above (with the new replacement sensor).

If you do not have such a tester, a normal multimeter (resistance and capacitance) should be sufficient

If you would like a transistor tester, you can search Aliexpress for one. It is an amasing little device. https://www.aliexpress.com/item/10050015…

Leasson learned: probe the oxygen sensor pins if you experience problems:

  • Pin 1-2 is the pre-heating element, and should show around 5-6 Ohm (meaning that the pre-heating must be using around 60W)All other combinations of pins should show a capacitance around 50 pF

There is a clear difference in the meassurements when comparing the defect part and the new replacement part.

Here are some good resources on Mazda and oxygen sensors, but remember: meassure the pins and look for signs of a defect device before you start taking tings apart

https://www.youtube.com/watch?v=jFFR4307…

https://www.youtube.com/watch?v=XC5HWd7P…

https://www.youtube.com/watch?v=fiOxH14J…

https://www.700r4transmissionhq.com/p013…

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Author

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                    LarsWH

Member since: 03/05/2016

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