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Oxygen sensor fitment

3K views 21 replies 6 participants last post by  AndreasPassat 
#1 ·
Greetings everyone,
Do any of you know if the downstream O2 Sensor Bank 1 will fit downstream Bank 2? There are 2 different numbers BOSCH*13550*(right) and BOSCH*13552 (left). I called Bosch and spoke with someone who told me one should work for both Banks, but the length may not be the same, that's why there are 2 different part numbers. I'm not buying into this as they both look like the same length to me. Has anyone replaced both? Are they different?
Any answer would be appreciated, thank you!

2000 Passat 2.8L ATQ M/T, FWD.
 
#3 ·
Should be the same with the only difference being the connector color. IIRC, the V6 has a brown and green connector to differentiate the left and right. Every other manufacturer just uses a black connector. If you really want to keep it OEM colors, de-pin the old connector that doesn't match and use on the new one.
 
#4 ·
Green connector is downstream right side
Brown connector is downstream left side
Black connector is for both upstream left and right positions

To answer your question...
Yes you can swap sides on the downstream sensors at the catalytic converters , but it will throw a CEL and it will detect the sensor is in the wrong position.
All (4) sensors have the exact same thread fitting that screws into the exhaust system.
 
#5 ·
I don't doubt you, but I wonder how the ECU knows. Is there something inside that sensor that tells the ECU what side it is supposed to be on? None of the other brands have a requirement of one side or the other.

I see where some AHA sensors indicate left and right, but the ATQ sensors do not.
 
#7 ·
I also don't know how the ECU could tell the difference, unless it changed the fuel mixture on one bank and saw a change on the other's sensor. My guess is that swapped downstream O2 sensor connectors might blame the wrong catalytic converter if only one of them was dying.

I'm no whiz when it comes to all the intricate electrical functions on our cars, but a few years ago I had used the Bosch generic downstream sensors and had the black connectors, when I got top side I got the (2) connectors crossed and within a short amount of time the CEL was on. Hooked up my VCDS and it said plain as day the O2 sensors were giving conflicting info.

My only guess is that even though the sensors themselves are identical, there must be a frequency or some type of modulation that's different between the left and right side.
If the downstream sensor is not reading the exact same set of data as the upstream sensor 'it knows'.
 
#6 ·
I also don't know how the ECU could tell the difference, unless it changed the fuel mixture on one bank and saw a change on the other's sensor. My guess is that swapped downstream O2 sensor connectors might blame the wrong catalytic converter if only one of them was dying.
 
#8 ·
I've seen other cars that could tell which cylinder (of 4) was mis-firing based on a single O2 sensor output so the O2 sensor may be able to detect the timing of each bank relative to its output. I agree there are no 'smarts' in the sensors themselves so it must be something the ECU can deduce by timing, frequency, one bank being tested at a time, etc.
 
#10 ·
I've seen other cars that could tell which cylinder (of 4) was mis-firing based on a single O2 sensor output
I believe that the way the ECU determines which cylinder is misfiring, is by noting changes in crank speed that don't match the acceleration /deceleration from normally firing cylinders. The O2 sensors react far to slowly to identify the cylinder involved.
 
#9 ·
Thank you all for responding. From what I have gathered, it is possible that I may have a CEL because of conflicting signals from both sensors. If this is the case, how come BOSCH supplies a universal sensor that works not only for Bank 1 and 2, but upstream as well.

From Bosch Part Finder:
Aspiration: Naturally Aspirated, Fuel: GAS, Position: Upstream,Downstream Left,Downstream Right, Engine VIN: D (my VIN is D).
Part Number: 15738
 
#11 ·
If this is the case, how come BOSCH supplies a universal sensor that works not only for Bank 1 and 2, but upstream as well.
Sorry about dragging all this technical stuff into the thread, just the nature of the forum beast.

It’s like comparing plugs and wires for the ignition system. All the plugs are interchangeable. So are the wires, but some wires are longer than others to reach the extents of the motor.

My biggest guess as to Bosch supplying a ‘generic’ O2 sensor is that they are significantly less cost than a genuine VW / Audi O2 sensor. I single Genuine VW / Audi sensor goes for around $215. If you need all (4) of them :icon_eek:.
The beauty of the Genuine’s, they are absolute plug and play. Correct length whether upstream or downstream and color coded to match the factory connectors under the hood.
Generic sensors require splicing in the connections to the original wire that feeds the O2 sensor and trimming to proper length. But they are usually around $45 per sensor. An absolute bargain but work is required.
For people who don’t know anything about how to wire up a connection or just the sheer fact they don’t want to mess around with splicing in an O2 sensor, the Genuine is the answer.
 
#16 ·
#20 ·
I'm going to throw this out there.

Within the next few weeks, I'm going to be required to ditch my WI license plates and apply for AZ plates, Which in turn will require an emissions test. With that being the case, I will certainly need to fix my current bad left side downstream O2 sensor.

I'm half tempted to purposely swap the downstream sensors and scan with VCDS and post results. I'm going to be laying under the car anyways and it'll only take a few extra minutes, so why not?

I am going to replace both downstream sensors with Genuine VW / Audi this time around. Call me anal, but the thought of a bunch of splices underneath my car really gnaws at me.
Plus my trusted sources has got them back in stock for around $80 :thumbup:
 
#21 ·
Just to be clear, I am not talking about generic sensors with bare wire. I am talking about the other brands that use the correct connector (but black) and correct length of wire, fully assembled.
 
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