Are All O2 Sensors Created Equal?

Nothing

 

No *****?

 

I also have been trying to educate myself on these fun little devices. I have replaced a few already on my 355. My experience so far has been better with the universal replacements vs the OEM ones from Bosch. Whether or not the Bosch OEM sold by the aftermarket suppliers are any different that the OEM ones sold through Ferrari I can't say.
I am intending at some point to post some photos and observations I have had with these.

So far my SWAG ( scientific wild a** guess) is that the universal ones appear to be more "forgiving" than the OEM ones I have used. By forgiving I mean aren't as susceptible to triggering an OBD code (pending or CEL). The universal ones appear to have a more open sensor design than the OEM style I have seen. This may ( and I say that with a large grain of salt) may account for a quicker response from the universal sensors I am currently using (just pre-cat so far).

Still trying to collect data on my own car. I have even spoken to the folks at Bosch but don't seem to be able to get anything conclusive. Lots of different reasons O2 sensors read the way they do and interpreting that information is challenging, especially for a novice like myself.

 

I just purchased 2 OEM bosch sensors for my 95 355 and both are fu......ed and I have to send them back. My mechanic says that they have had poor results with the aftermarket ones that you have to splice because they come without the plug. I dont know what to use next.

 

Rule # 1 (at least in my experience) I solder the connections, toss out the splice kit they supply. The OEM style I ordered with plug gave me problems so go figure!

 

here is what i have been able to gather about 02 sensors over the years. First, an explanation of how they work for the 2 different varieties that exist..

The main distinguishing factor for an oxygen sensor is its resolution, expressed as a voltage level. There are 2 types of oxygen sensors, usually referred to by their resolution capabilities. The first type, referred to as a "narrowband", has a resolution that is very very small. This type outputs a voltage of usually 1 volt when the air/fuel ratio is below ideal stoichiometric mix of 14.7:1, and a voltage of 0 when above 14.7:1. These narrowbands are more of an on off switch for rich or lean conditions, and provide no real info regarding how rich or how lean the exhaust gas mixture is.

The second variety is referred to as a "wideband", and these typically output a voltage of near 0 volts for really rich conditions, like 10:1 or lower a/f ratio, and typically put out 5 volts for severly lean conditions, like 18-19:1 a/f ratio. These wideband sensors tell you how rich, or how lean. You will also note that the wideband sensor is backwards, in comparison to the narrowband. For a narrowband, 1 volt is output for conditions below 14.7:1 stoich, while the wideband outputs some voltage between 0v and 2.5 volts for below stoich. It is important to match the type of 02 sensor to the type your car needs.

Additionally, o2 sensors come in different wiring configurations, generally depending on if they are heated or not. Heating the o2 sensor provides more accurate readings earlier in the engine cycle, for things like cold starts and such. Unheated narrowband o2 sensors are generally 1 wire or 2 wire sensors, while heated narrowband o2 sensors are 3 or 4 wire. Wideband sensors are always heated and are 5 wires or more, at least in my experience, so by simply counting the number of wires going to your o2 sensor, you may be able to get an idea of what kind of sensor your car requires. An interesting tidbit is the 2002 Volkswagen Jetta 1.8t came with both a narrowband and a wideband o2 sensor , so for those of you with Ferraris requiring widebands, you may be able to use that vehicle as a cover for the wideband sensor you need, but get it for much cheaper from a generic auto parts store because "its for a volkswagen"

The main difference i have seen as far as the "universal" o2 sensors are concerned is that they do not come with the harness clip specific to your car. They are not simply plug and play. You get the o2 sensor with a bare wire coming out the back, and you get to wire it to the existing wiring in your car. In my opinion, these universal types are a PITA, because its not a simple soldering job to swap them out, because the solder will melt because of the extreme temps in the area of the o2 sensor. The proper way would be to use some high temp wire crimp connectors, which are not generally easily available, which is why i recommend buying the o2 sensor specific to your car, and not the universal ones. That said, the universal ones are generally the same exact spec your car requires, it just doesn't have a harness plug to plug and play into your existing harness. you have to take your old o2 sensor out and chop of the connector, then rewire the old connector to the new sensor.

If anyone wants to read up on it, here is some more information http://mycomputerninja.com/~jon/www.pgmfi.org/twiki/bin/view/Library/WideBandO2.html

 

Thanks Alberto. That is the exact # of the ones I took out and the new ones I installed. The SD1 tells us that the one is dead and the other works but not good at all. The old ones were in better shape.

 

You can always try the Bosch universal equivalent #15727. You will need to splice your old plug onto it though. As mentioned, solder only, and use heat shrink tubing on all four splices, plus one larger piece over all of them.

 

As Rifledriver stated, nothing. They ARE all different. I have used on my 5.2 motronic 355 both the factory oem Bosch pre-cat O2 sensor #13819 and the Bosch "universal" equivalent, # 15730 which required me to splice my old plug onto it. Both worked perfectly. BUT, we have seen on this forum, people who have put post cat O2 sensors in the pre cat location, and vice versa with bad results, and "check engine" lights. Even though both O2 sensors are four wire, heated O2 sensors, there are definitely differences that the Motronic can detect. You must use the correct ones, whether oem with the correct length cable and plug, or the correct "universal" equivalent, that will require you to measure and splice your old plug onto it.

In other words, you cannot simply purchase any "universal" O2 sensor that has the correct number of wires and threading, there seems to be more to it than that, and you should check with Bosch to ensure you are getting the correct one:
Bosch Customer Service:

888-715-3616
(Monday thru Friday 8:00 am to 5:00 pm CST; for U.S.)

 

I thought the bosch equivalent was 15719 but I may be wrong. Where do you get them? I heard they are a ton cheaper like under $30.

 

Franco----RockAuto breaks all the different ones down.. Let the catalog load and then pick Ferrari 355 and your year..


http://www.rockauto.com/catalog/raframecatalog.php

 

Not that cheap....more like around $60 ($52 at www.rockauto.com). You want the # 15727.

 

NEVER Solder the o2 signal wire. You will throw out the readings its giving to the ECU.The kits come with special connectors for a reason. use them. I personally never use the universal units, I have found they are more of a pain in the butt then anything. Just anti-up the 300 bucks and do it right. There is nothing worse then opening the hood and finding a botched electrical connection.

 

+1 and then some!

The next statement I hear often is "It cant be the O2 sensor as I just went through the whole system and replaced those".

There was an excellent reply to a O2 sensor question by a Bosch executive on this site a few years back, I wish I could find it and repost each time the question pops up. There are so many minute issues with these components that few understand. Baseline sample air being drawn through a wire, how quickly exposure to silicones will destroy them.....

Look hard enough and most everything can be explained. One particular wax when applied to the hood of a 550 will kill all 4 O2 sensors. I found a small amount of what was thrown off the buffing wheel in the hood snorkel after the third set of 4 was replaced. How long do you figure that took to analize? They were all Factory supplied sensors and would only last 3 months! I would have never guessed they were as sensitive as they are but changing wax and taping off the snorkel durning a buff has eliminated the problem.

Spend the money and buy the correct ones!

Dave

 

Ok, I let you take a shot at me. I fail to see how a solder connection is inferior to a splice kit connection? Please explain how a solder connection (done correctly) is going to throw off the ECU. Like they say, you can learn something new every day!

Steve

 

I tried a google search and got a few threads on other sites, but no official statement from Bosch...but it goes along the lines of what Dave Helms stated: "Baseline sample air being drawn through a wire... " The claim is that an air sample is drawn through the wires attached to the O2 sensor, so if you solder and heat shrink the connections, you are essentially sealing the wire off, and the O2 sensors ability to take that air sample. This is a copy of the instructions that came with my Bosch universal O2 sensor I am using on the drivers side pre cat, has been working fine for about one year. Soldered the connections, I must have got lucky.

http://www.boschautoparts.com/NR/rdonlyres/3BB8A8FA-C707-4333-9098-727C01AF4B7D/0/OxygenSensorInstall.pdf

Interesting that if this is true, why Bosch does not more clearly warn that you must use their splicing block, and NOT to solder in the instruction.

BUT....if you read this pdf description online by Bosch on their various sensors: http://www.bosch-motorsport.de/pdf/sensors/lambda/LSM_11.pdf

You find this confirming statement:

"The sensor receives the reference air through
the connection cable. This means that the
connector must be clean and dry. Contact
spray, and anti-corrosion agents etc. are
forbidden.
The connection cable must not be soldered. It must
only be crimped, clamped, or secured by screws."

 

Actually, there are errors in the Rockauto application guide related to the 5.2 355's from 1996 to 1999. In fact the errors came from Bosch and are repeated in almost all the online guides.

These are the correct 5.2 O2 sensor part numbers:

pre cat
Oem Bosch, ready to install : 13819

Bosch Universal: 15730

post cat
Oem Bosch, ready to install: 13820

Bosch Universal: 15738


2.7 O2 part numbers are:

Oem Bosch, ready to install: 13309

Bosch universal: 15727

 

This is why you guys are invaluable here, to save us from ourselves!!

 

Do not take it as a personal shot. These details have only come to light a few years back when the O2 sensors started on a rapid evolution from the single wire units used for years. Even in the industry we were in the dark until we uncovered internal reports from the manufactures.

I believe the concern is more related to the flux of the solder contaminating the referance air sample. In the late 90's I found we could make some of the O2 sensors come back to life if we removed the seals in the weatherpac connectors. Who would have thunk they were sucking air down the wires, surely not me!

Dave

 

It seems like this information is a secret to the manufacturers as well. Everyone you ask has a different answer and people at Bosch are famous for "I'll get back to you".

It's curious that Ferraris seem to have issues with O2 sensor problems. Cars have used them for a couple decades now and a failure on "daily drivers" is pretty rare. I've only ever replaced a few on "other" cars.

 

"Other" cars aren't buffed and detailed to the extent these are would be one excuse I see and have dealt with. There were a number of interesting details we were told by a Bosch engineer working for Ferrari when we were at the factory for 360 training that I cant speak about. So much information can be obtained when the Grappa is uncorked.

Dave