Denso 234-9123 Oxygen Sensor (Air And Fuel Ratio Sensor), Regular (2349123)

I own a 2008 5MT Outback with over 200k. The car has been fantastic. For the last couple years I've been getting a random "Catalyzer below threshold" code. I thought it was time to replace the cat converter (not surprising giving the miles). But I decided to try the anti fouler bung on the O2 sensor. It worked for a while, but my check engine light kept coming back while in the highway, disabling my cruise control (some "lean condition" code. On these Subarus, and many newer cars, the downstream sensor (after the converter), is not only to check the efficiency of the converter but also has something to do with the fuel trim). I finally decided to replace both O2 sensors (the car well deserves new sensors after all these years), and sure enough, the check engine light has not returned, engine runs smoother, and I should expect some improvement in the fuel mileage. So, if you're on the same boat, replacing both O2 sensors quite probably will do the trick, and it's way cheaper than the catalytic converter. One last thing....as many people before me pointed out...don't use cheaper sensors. These Denso ones are OEM, and work fine.

Fit my 2009 Forester non turbo perfectly. The length was exactly like the original and even had the original style lead clip.

It works perfectly

Perfect fit in my 2006 Forester X. Matched OEM part exactly, down to the clip, plug, even insulator color. Comes complete with the anti seize grease. In some cars, you can use a 7/8" or 22mm open end wrench, but in the 06 Forester, there just wasn't much room to apply the torque needed to break it free. I bought the crow's foot type split socket to use with a long extension bar and breaker bar. Once it moved the first tiny bit, it was pretty easy to remove and replace from under the hood. You just have to be a little bit of a contortionist. Unhook the negative terminal of the battery while you work to erase the engine computer, so it will "learn" this new sensor. The car will seem very hard to start the first time after replacing. That's normal. Start the car with all high power items turned off and without touching the gas pedal, or even the brake pedal (pulls vacuum from the engine and affects the way it runs), and let it idle for about 10 minutes until the temperature gauge reads normal operating temperature and the idle speed stabilized to its normal speed. Then turn on the AC full blast, the rear window, headlights, etc, and let idle a few more minutes, to let the computer learn the sensor under some load. My car has been intermittently throwing check engine light codes related to catalyst working below threshold, and post catalyst trim too rich. I'm changing both the upstream and downstream sensors out to see if that fixes the problem. The original ones have about 180,000 miles on them and are probably bad, or going bad. Both had a bit of fluffy looking black carbon deposits on them, an indication of rich running.

THIS FITS 2006 SUBARU FORESTER 2.5X WIRING HARNESS COUPLER WITH SOME WIGGLIN!

I bought this as an upstream sensor for 2007 Subaru with a 2.5 liter engine to replace an original after 225,000 miles. It came with some copper anti-seize compound. It looked like the original with one important exception-the wire connector was different than the original one in my car. I checked the part number several times, and even ordered another one from my local parts store to check it-the numbers match but the connector is different. Perhaps there was a change made after my car was made. Because I needed to get my car back together, I cut the connectors off and swapped my original onto the new sensor-the wires are the same, so it was just a minor challenge, but cutting into an expensive part made me nervous. The sensor has worked well-no check engine light, and the scanner showed fast response and good fuel trims. After almost 6 months and more than 10,000 miles, this is still working. There have been no error codes, fuel mileage is what I would expect and the engine runs great. Update. Almost 2 years later the engine is still running strong, good fuel trim, no sensor-related check engine light. Update. I got another one of these for another car, and in the process learned why I thought the connector was wrong. It has a plastic protective piece that I thought was part of the connector itself. Removal of the piece revealed the correct connector. That was a critical thinking problem on my part, and realizing the error of my ways has hopefully made me a better person in some small way.

it fit perfectly as far as the connector was identical oem. you want to only go with denso which is the oem supplier for subaru. price from this vendor is great, best i have seen anywhere. new at oreilly etc was $50 more cost! ck engine lite went out immed, car runs so much better as this going bad really messes up the fuel mixture- makes car run rich, so gas mileage is better and it runs way better, more power etc. this is the upstream 02 sensor, which is the one that takes the worst beating of the two 02 sensors in any vehicle. it should be replaced about every 80k miles, the downstream one can go longer. funny but my ck engine lights just got thrown, runs fine but something threw that, could be downstream sensor but car only has 90k miles so it should not be going bad this soon. supposed to go like 150k or more even because its downstream of the catalytic converter so it gets cleaner air and doesnt go down as fast as upstream which gets raw untreated exhaust. i did a ohm test on downstream and it was in spec, i did upstream prior to replacement and it was showing out of spec. ck engine analysis cemented the fact it needed replacement at about 90k mi, but actually the lite was throwing at about 84k. newer subarus are more sensitive to sensors, mine is a 2010. 2008 and older are not nearly as effected by sensor health as 2009 and newer.

Replaced the front A/F sensor with this OEM part, fit perfectly and works perfectly, spend the extra to have a quality name brand, I had previously purchased a non name brand, trying to save some cash, it lasted 1 week, it looked the same until I actually measured the 2 sensors, the no name was actually longer, and the car kept throwing codes, once replaced with the Denso sensor, no more codes

Le quedó de maravilla a mi camioneta y la misma marca y el mismo modelo funcionó correctamente.

i’m not recommended it’s doesn’t work bought it last year and now have same issues so disappointed cheers

Fit my 07 Subie Outback and got rid of my CEL code. Easy to install and less than half the price of dealer part.

Exact replacement fit perfectly and no issues once installed.