Hey everyone,

I am aware there are endless threads here explaining how to change them, I do though need some help identifying which sensors to buy, as I know hardly anything about this kind of stuff, I understand getting low quality ones may end up causing additional damage to other engine components, which obviously isn't anything anyone wants to sit and think about just because they cheaped out.

Now, I've found loads of different variants from 10+ different makers varying from about €30 each up to €150 PER SENSOR which I feel is absolutely ridiculous. I am looking to replace all four of them. What should I look for in a lambda sensor? What is a reasonable price? Is there any point looking for used ones?

Kind regards,
Arvid

 

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JaguArvid, one thing that I will tell you is getting the correct tool will also make a big difference. You will find a lot of places sell what looks like a socket with a hole cut in the side. Do not waste your time and money with these. They work fine if you are replacing the O2 sensors often and they are not tightened really tight. Otherwise, as you apply force, the socket will open up and slip on you. What you are after is what will look like the bottom half of a socket (has a slot cut in the far side) with a short handle off to the side that you can put your ratchet into. They will look very similar to this:


If you use a socket and then one of these, you will understand what I am saying. They are fairly cheap and well worth the money. I would recommend getting one with a 1/2" drive in case you need to get some serious leverage to break things loose.

To help clarify some of the confusion that you may be seeing is that some are called O2 sensors and others are called air-to-fuel mixture sensors. they both do about the same job, but they are in different locations. so, you need to pay attention. They are not necessarily interchangeable. The sensor downstream of your catalytic converters are your oxygen (O2) sensors. They do exactly what their name says, they measure the amount of oxygen left in the exhaust. If your catalytic converter is doing what it should, there should be near zero oxygen on the downstream side of the cat. if there is zero, this triggers the car to say that it is not running correctly. If there is too much, then the cat is not burning the unburnt fuel and is an emissions issue.

The sensor between the engine and the cat (in our case is mounted into the side of the cat) is your air to fuel mixture sensor. This is measuring the oxygen levels in the exhaust, but it is also seeing the unburnt fuel too. This signal is then fed back to the computer to adjust the amount of fuel put into each cylinder based on where the throttle is.

As for what sensors to buy, I would say to first stay away from anything that says it is universal (especially if it is saying that you need to connect up your own wires). Yes, they are dirt cheap, but if you talk to a lot of the members here, you are likely to have lots of problems and in the end will probably end up buying the other sensors anyways. From there, stick with names that you are familiar with. The factory ones were made by Denso.

One last tidbit, if you look, you will see a black connector next to a gray connector. If I am remembering things correctly, the gray connectors are your air-to-fuel sensors and the black connectors are your downstream sensors. This is a quick check to make when ordering new sensors to make sure you don't install the wrong sensor in a location.

 

Additionally, buy the millimeter one. That little bit of difference DOES make a difference when removing a stubborn sensor. There's a thread with a member (who left because of a mod) who had that exact problem getting his removed. When he switched to the millimeter one, it came right out without rounding the edges.

 

Right, thank you both for your helpful advice.

Thermo, I understand that they do two different (but very similar jobs), but can they be the same part? Or do I have to order two different type of o2-sensors, this indeed is very confusing to me

One of the sensors I was looking for is indeed from DENSO, the company you mentioned made the OEM part, this one is a universal one which they say shall fit the X-type saloon and estate of all model years, I will add a link so you can see the part details (https://www.onlinecarparts.co.uk/denso-1665307.html). Now, still, would this be a bad option to the oem part which costs not even twice as much, but three or four times as much.. There is a Swedish site which will sell me this exact part with a two year warranty, doesn't sound like much but I guess it's more than enough to try and see the quality of them.

What do you think? I am very thankful for your experienced advices

 

I ordered both upstream and downstream from rockauto, with shipping and import charges cheaper than local store. And with OEM Denso part numbers.
https://www.rockauto.com/en/catalog/...2)+sensor,5132

 

JaguArvid, you need to order the two different sensors. People have tried using the same sensors and they have all had issues.

 

Right, I've found two types of Denso sensors now which should fit my car.

o2 sensor part number DOX-0113 ~€45/each
a/f sensor part number DOX-0430 ~€120/each
You can see them here if you want DENSO E-catalogue - Denso

Will order them and update here if it worked out whenever they appear in the mail, thanks a lot for your quick expert advice.

 

And remember you have 2 of each kind (4 total) for replacement on both catalytic converters.

 

Aye, I did order two of each, hopefully arrive some time in the middle of next week, if so I will put them in during the weekend right after, will write here and update after

 

 

MIL should go off (if fault fixed) after 3 (maybe 4) warm ups - mine did with a P1647.

The DTC will stay harmlessly stored for 40/80 warm ups.

 

Great news!

After I changed the B1S1 I went for a drive (trying to complete the upstream oxygen sensor drive cycle). Nothing happened with the light, but tonight as we got in the car to drive to my cousins' birthday thingy the MIL just went out as soon as I starter her up!

Feels great I have to say!

 

Usually O2 sensors die for some reason and replacing them leads to killing of new sensors.
Example:
dead ignition coil or injector kills o2 sensor AND catalytic converter and of course replacing sensor and converter is useless. New sensor and converter will die pretty soon.
This is what happened to my X.
Dead coil killed o2 sensor, so i replaced coil and o2 sensor. I had to replace 3 coils (that is why I bought the car dirt cheap)
You need to check live data or ask somebody who can to make sure your new sensor is ok.

 

1647 and 1648 are heater failed indications, these seem to be the most common faults. the heater cct is turned on when the engine is started to heat the sensor so the ecu can go from open loop to closed loop quicker, once the engine is running the exhaust gas heats the sensor and the heater is no longer needed, unfortunately the ecu does not turn the heater off so its on all the time. if it were turned off they may last longer.

 

That sounds reasonable, I do have a reader with which I can check live data. Could you specify what I should look for if you know? Would help my worrying a lot. Also, can I check the status of my ignition coils or injectors without removing them? As of now I have no error codes at all.

Hmm I never had those codes but I had p1646, p1647 is bank 1 sensor 2 right? The black connector next to the grey one I changed.

 

you are fine if:
1.no codes
2.engine doesn't shake sometimes(intermittent ign. coil problem)
3.short trims are OK

Ignition coils usually die around 100-150k miles.
I went to junk yard and found X with new coils (they look different)