Denso234-9122 Oxygen Sensor (Air and Fuel Ratio Sensor)

My 2005 Subaru Legacy complained about needing an O2 sensor, and I considered buying one of the no-name cheaper ones instead of a Denso - but after ready the reviews on half of them to see tons coming DOA or failing after a short time, I decided to stick with OEM and get a Denso.Relatively easy to install on my Subaru, I was able to sneak in on the passenger side of the engine, right behind the valve cover, and break it loose with a wrench and thread it out/install the new one. After doing an idle relearn (Dont forget to do that, at least on Subarus!), the car ran perfect and I have not had a CEL since!I've never had an issue with a Denso - I'd recommend you pay up for one, unless you want to replace it a few times.

I decided to replace the upstream o2 sensor for my 2005 Subaru legacy 2.5i after discovering the CEL for "P0131 Bank 1, sensor 1 low voltage". It's the EXACT oem replacement. Initially I didn't screw it in tight enough due to the restricted space, but once I did, the check engine light went off and the cruise control started working again AFTER I reset the code with a diagnostic cpu. Much better than $300 at the mechanic.

In my experience, Subies like either Subaru branded parts or Denso. Considering position of this sensor on CAT and time involved replacing it, it's not worth saving $30 on an "off-brand" sensor. A typical oxygen sensor socket really doesn't work- just use a 19mm combination wrench turning 5-10 degrees per go until loosened enough to use your hand. Other reviews mentioned it wouldn't fit the 05's, but this fit mine ("i" model) perfectly. There are several variations of the 05 (SOHC, DOHC, turbo, 6 cylinder, etc.), and at least 4 different A/F sensors, so verify BEFORE ordering! Color of connector is different, but wiring matches correctly. It comes with the correct anti-sieze compound, which is nice. Also has the correct plastic clip to route cable and keep it out of harms way. Don't forget to use dielectric grease when plugging back into harness.

Great value. Part fit and worked well. Unaware I needed two sensors on the catalytic converter. Still..cheaper than the auto parts store where I had to purchase the second one.

Exact same product as OEM. No issues with product quality. However DOES NOT plug right in to 2005 Forester. Neither does the same part right from Subaru. I had to splice the old plug on to this one. There must be a problem with the replacement sensors. I bought 3 Denso ones and 1 OE one from the dealer (same Denso sensor) all had the same story. Returned other sensors, used this one as it was the cheapest of the 4. Cut and spliced my end on to it and works great, as expected.

Easy replacement, fit perfectly and cured my issue. I will mention that I dropped the exhaust system off the engine (and a hanger bracket) in order to get enough room to get this thing replaced. This was a simple process and took only 30 minutes, start to finish.

For my 05 subaru legacy, this sensor did NOT fit. It will claim to but the connector is different, so before you put in the tedious work of getting the old one out and putting this one in, check the connections because in this case i was VERY misled and it cost me a lot of time and money.I recommend going to a parts store, it may cost you more but then you'll know you are getting the correct product and if you aren't they will be right there so you can prove it to them.

This is OEM rated, and so far no check engine light or other issues after having it installed. Our old upstream sensor in our 2005 Subaru Outback went bad, and after they charged us $80 for a full diagnostic check, I did not feel like paying the dealership prices for the sensor and the labor (They quoted us at $240 for the sensor and $520 for the total job!).Found this one for under $100 and had it installed at a local mechanic who did not charge us for labor as he was doing other work in the engine at the time. So basically we saved $420, very nice.