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I have a 2004 BMW 325i base model and I want to DIY the sensors. I’ve bought some but it didn’t fit. I really need help finding the right sensor ✊🏾
 

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2004 330Ci 85k miles
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Which O2 sensors? There are 2 pre-cat and 2 post-cat. I’d guess you want to replace the 2 pre-cat sensors?

Look up your BMW part numbers on realoem.com, then buy them from fcpeuro.com.

Sooo, what makes you think you should replace the O2 sensors? You have a trouble code that mentions them?
Post the trouble codes with their descriptions and let’s see.
 

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Discussion Starter #3
Which O2 sensors? There are 2 pre-cat and 2 post-cat. I’d guess you want to replace the 2 pre-cat sensors?

Look up your BMW part numbers on realoem.com, then buy them from fcpeuro.com.

Sooo, what makes you think you should replace the O2 sensors? You have a trouble code that mentions them?
Post the trouble codes with their descriptions and let’s see.
I got the code from auto zone and don’t have a copy. It’s all 4 sensors that need replacing. Going to lookup the part numbers on that website
 

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Bosch O2 sensors for a M54 engine, are Upstream front and rear = 17215; Downstream = 15680 front & 15681 rear.
A M56 SULEV engine requires different part numbers. 17175,17176 for Upstream, downstream are the same.

realoem will tell you what engine you have, if you don't know, by typing in your last 7 digits of your VIN.
 

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To find part numbers for your car go to www.realoem.com and enter the last 7 characters of the car’s vehicle identification number. You’ll find it on your registration card and in the bottom of the windshield on the drivers side of the car. After entering the characters hit enter and bookmark the page. BMW, being German, has laid things out very logically. Different systems are assigned a 2 digit code. For example, almost all parts for the brakes being with “34.” Interior parts, except the seats, being with “51.” Seat parts being with “52.” Them Germans.
 

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Discussion Starter #10
You guys are great! 😭 unfortunately my expansion tank just blew up so I have to worry about that now.
 

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Discussion Starter #11
Bosch O2 sensors for a M54 engine, are Upstream front and rear = 17215; Downstream = 15680 front & 15681 rear.
A M56 SULEV engine requires different part numbers. 17175,17176 for Upstream, downstream are the same.

realoem will tell you what engine you have, if you don't know, by typing in your last 7 digits of your VIN.
It is M54. Thank you so much!!
 

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Of course that's what AutoZone said as they want to sell you O2 Sensors at $80 each. You really need to post any error codes you have. If you don't have an OBDII Code Reader, buy one. I have the U480 and it works fine for reading and clearing codes.

My car isn’t mobile right now to go get a diagnostic but the guy that helped me with my car has a scanner and he told me that all 4 sensors are out
 

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Do I need to verify part numbers?
From what I read so far, you had someone scan the car for trouble codes, don’t know the trouble code number or description, and are blindly following this person’s advice to replace all four O2 sensors. That right?
 

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And you don’t need to replace the downstream ones
unless they are giving heater codes.

OP, replace your cooling system staying AWAY from the 'Zone.
Modine or BMW expansion tank, Nissens radiator, and
good quality hoses.

Then it's time to get yourself a scanner or 2
(cheap compared to the cost on ONE oxygen sensor)
and learn how to read and interpret codes.

We can help with most of that.

t
 

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My E39 has 400k miles and my front O2 sensors are of an unknown age and, using live data in INPA, looked a little tired ( less responsive). I needed Bosch 13477 for my 530i. I found them on Amazon with a damaged packaging - possible a returned item for $35 ea..about half off.

FCP Euro is a great option with lifetime replacement, but the price on Amazon was too good to pass up.
 

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BTW - Bosch O2 sensors have a date code stamped in the black plastic connector...at least mine did.
The ones I removed from my vehicle were made in 2016....pretty new ! There may have been only 15k miles on my car since. 2016...I bought it as a non-runner and then did a manual swap..it has been off the road for at least 12 months since 2016.

So, you can check the age of your O2 sensors without even unscrewing them..Just unplug one of them and look at the code on the connector...It's small. ..I have just been checking the age of all the O2 sensors on my cars..
 

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Why not the downstream?
The downstream are mainly used to monitor the condition of the cats, so they can be neglected for much longer that the upstream sensors that are used to fine tune the air fuel mixtures ...

...but it depends on the specific codes.

You really should not be relying on others to scan the car for you. Get OBDFusion and a bluetooth elm327 interface and read codes yourself so you know what specifically is going on.
 
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