WTB: Front O2 Sensor For a 2L
 

I threw a P1130 CEL (according to my AP V.1 which I just read may not be trustworthy for reading some codes) code on the way to work today. I just reset the ECU after reading the code so I'll wait for it to come back again before doing anything drastic, but just a feeler to see if anyone has a used one or even one I could borrow to verify it's the issue.

I have a feeling it's my craptastic wiring fix failing. 5 years ago when I installed my UP, I cut all 4 or 5 wires to that sensor and had to use butt connectors to fix them. The CEL description makes it seem likely:

Sounds like repairing the connection might be worth a try.

I have a stock STI one handy if it is the same.

Thanks, but all 2.5L ones are different from mine.

You can get cheaper sensors at Kragen, but they come with a generic harness you have to wire yourself.

Also, don't bad o2 sensors come up as "open circuit". My guess is that if the wiring was fine for a long while, it's more likely the sensor is bad than the wiring suddenly.

Usually bad O2 sensors show up as a converter code, because they start sending out bad signals. I don't think they fail completely like that, but it's possible.

I'd like to have a new sensor in hand before I rip it apart so if the wiring looks good still, I could just pop in the new sensor. Who knows though, maybe the CEL won't come back. I haven't actually started the car since resetting the ECU.

If you used crimp butt connectors, they could easily be oxidized and failing. Solder and heat shrink tubing is the only way to go especially for something exposed to the elements.

Good info from the manuals on how to diagnose the open circuit code, here:

http://forums.nasioc.com/forums/show...2&postcount=25

I'll try, but I really suck at soldering. I think I have solder and tubing, but my solder gun is an antique.

CEL didn't return with a quick drive around the block. We'll see if it comes back eventually.

For this sort of thing a classic Weller gun or similar is perfect. Basic design hasn't changed in probably 50 years.

happy to help if you need it.

Just make sure the tip is tight in the chucks and tip is clean/tinned.

Wire is clean not oxidized.

Remember to put the tubing on first and slip it back at least a few inches if possible.
Twist the wires together in-line.
Put some solder (rosin core) on the tip and put it on the wire.
Feed additional solder onto the wire when hot.
Just enough to fill the gaps, not make a blob.
Move the tip if one area is not flowing.
Keep it still while cooling to solid. Should appear shinny not hazy.

It really is not that bad if you take your time and do the prep. Lot's of web sites out there on proper technique, but it is not anywhere near as tough as welding.

Crimp connectors are just plain bad for almost any use. Only thing worse is those vampire connections.

Usually when I solder wiring (not sensitive electronics), I don't even use a soldering gun.... just use a propane torch. Although you use more solder, it goes much faster...

Well, I've driven a few times now, and put about 40 miles on the car since resetting the ECU and the CEL hasn't returned, yet anyway.

All this talk of how to solder, and no one points out that you're not supposed to solder O2 or EGT sensor wires?

Solder can change the reading if you're not super good at soldering... the dissimilar metals can change the voltage read by the sensor.

But all that's moot if the wire is stainless steel. You're not going to get that to work unless you're buying special solder.

Did not know they were that sensitive. Butt joints have to be much worse than solder from a voltage drop/resistance perspective. If they are that sensitive, that would mean the length of cable has to be correct and any "extension" cables would be bad as well.

Soldering anything other than copper or nickel requires special stuff and silver solder or ??? Heck, soldering some types of coated or nylon core copper can be a real PITA.

When one of my wholesale customers (mechanic or shop owner) wants an O2 sensor, they get the one with the factory plug on it. Even the cheapskate ones still don't buy the universal ones, so take that for what it's worth. Even if a sensor reads bad because of a faulty wire, most of the time they replace the sensor rather than repair the wire.

As far as the best way to make connections, I've always been taught that a proper crimped connection is superior to soldering. This assumes using the proper size connector for the wire, using a quality connector, and using the proper tool to make the crimp. Soldering is harder to do properly (for most people), less flexible and less resistant to vibration. I'm not saying a proper solder joint wouldn't work, and the crimp vs. solder debate can go on forever.

In the case of external wiring on a vehicle, I would use crimp connectors with heatshrink over them to protect from the elements. A properly done crimp will have no appreciable voltage drop on a 12v automotive electrical system.

This is almost as much of a religious war as springs vs. sway bars in Interwebland.

The real answer is using the right connection and the right tools for the situation.

Cheap crimp connectors crimped with a $6 crimp tool are likely going to be a problem over time. These are a common failure in automotive arena from car stereo to engine harness and don't get me started on trailer wiring. I can't tell you how many of those I have had to repair over the years on all the trailers I have had. The only way I have ever seen a proper solder joint fail is when it was improperly supported and flexed, fatigued and broke. Solder joints do not bend and have to be handled as such and just like a crimp have to be done correctly.

Any joint or connection can be enough of a change in a sensor circuit to cause issues depending on the sensor. Every inch of wire and connection has a certain amount of loss inherent in it and/or will act as an antenna in some manner.

In these days of sensor controlled engines, some of the days of shade tree wiring harness repair are over. If a sensor is accurate to the millivolt, milliamp, ohm or digital in nature and susceptible to RF they will have a fixed length cable with a spec wire and connector. Thinking about my wide band 02 sensor, I recall them strongly discouraging any cable modifications.

Clearly, the only choice is to solder your crimp connectors.

:lol:

I remembered after making the first post that I re-did the butt connectors when I was fixing an UP leak about a year ago. The connectors and wire all looked just fine so corrosion doesn't appear to be an issue. I'm sure the large quantity of electrical tape that I use to seal each conection seperately and then to bundle them all together helps. If there is any issue with voltage drop due to the connectors, it hasn't become evident.

The CEL still has not returned.

This. Not worth the time, as far as I'm concerned, to attempt putting together wiring on an engine sensor. And not just with customer cars, I replace the entire thing with factory connected parts on my own car as well.


/$0.02

How do you know the AFR calibration isn't off? This would not cause a CEL, but maybe the AFR is actually 15.x:1 or 13.x:1 instead of 14.7:1.

I don't know for sure, but it's been like this for over 5 years and my car always runs great and has been more dependable than I expected (I'm at 125K miles, most of them stage II and I've autocrossed for 5 years). In the last 5 years It's been tuned/logged with wideband by Ed a few times at sea level and this elevation and always get's thumbs up from Ed, though my stock injectors hold me back a little at sea level.

I guess there's a chance that a connection could/has become loose which could cause an emerging issue where the ECU is getting fed bad AFR data though...but it's hard to justify the $ and time to replace the O2 sensor without more evidence IMHO.

CEL still has not returned.

It is a pretty easy swap and if it is the stock one, 125K is a long time on 1 sensor.

I think typical life time for an O2 sensor is 100K assuming it is heated, 50K if not. Not replacing it could cost you the motor. Cheap insurance for < $100. Just saying...

I have the cool slotted socket if you want to borrow it.

I've got that socket too, but thanks. They're closer to $200 shipped (from subarugenuineparts.com anyway).

Maybe I'll grab one next time one of the online Suby parts places emails me a 15% off code or something. If the CEL returns, I'll be more motivated.

It is a Denso 234-9011 and can be had for $95 on ebay, $118 on Amazon and $133 at Rock Auto.

Does everyone else agree that it's okay to go for that? I kinda took Cory's statement to heart that he sticks with Factory parts...plus that's always been my sentiment too.

Is that with the OEM Subaru connector on it? Because I remember not being able to get one for under $150.

I think the non-OEM sensors are fine. It's the crappy non-OEM do-it-yourself connectors they come with that are the problem.

There is a cross reference to Bosch, NGK, etc. but AFAIK the Denso is the OEM for the Subaru sensor.

From everything I just read, it is Plug & play.

ACDelco - 213-2843
Airtex - 5S4302
Bosch - 15537
Denso - 234-9011
NGK - 24659
Subaru - 22641AA042
Walker - 250-54004

Denso is an OEM supplier for many electronic parts for JDM manufacturers. I'd have no trouble putting one in my car.

Maybe my earlier statement is adding to the confusion, let me try to clear it up.

Most aftermarket sensors are fine to use, I would have no problem recommending Denso, Bosch, NGK, etc. Just make sure you get the one with an OE style connector on it. The ones to avoid are usually called "universal" and they come with no plug on the end. You are supposed to cut the stock plug off your original sensor and splice it on to the new one. Which is basically what Cody has done, except it's still the OEM sensor. These are usually less expensive, but like I said most mechanics that I know will not use them.

As Khail just mentioned, I think I was a bit confusing as well... It's not that the part is specifically the factory part, simply that I get the aftermarket one that has the factory connector, in order to avoid having to cut and splice wiring.

Thanks for clarifying guys. According to several posts on Nabisco, Denso makes the OEM sensor anyway, which isn't surprising since I've seen "Denso" printed on other sensors on the car.

Some even claim that Denso makes all of the aftermarket ones too (rebranded), since it's a unique-to-2L-WRX sensor and most manufacturers can't justify making the small qty that the small demand warrants.

The same CEL came back today so I ordered the sensor from Amazon. Hopefully it ships from Fernley and gets here in a day so.