Help: Bad O2 sensor....s?

2005 legacy 2.5i

Help. Can anyone explain the odds of both O2 sensors going bad within a week. A couple of weeks ago my check engine light came on. At first I thought it was a loose gas cap as has happened in the past. When the light didnt go out I took the car to my mechanic (not dealer) who does do diagnostic work. He told me that the down stream O2 sensor was bad. I had it replaced ($250.00) and the check engine light was reset. About 4 days and 50 miles after picking up my car my CEL is back on. My mechanic now says that the up stream O2 sensor is throwing the code. My mechanic is pretty trust worthy but I cant help think that the odds of both sensors going bad are pretty high. He has offered to replace it for parts cost only and no labor. He did not replace it yet, reset the light and told me to drive it for a few days to see if the problem comes back. He said he does not want to needlessly take my money.

 

What are the odds of this and what else could cause this?

My car only has 42,000 miles on it and i meticulously maintained.

O2 sensors are expensive.

try www.sparkplugs.com for your plugs. might be cheaper to get them there. did he tell you what codes are popping up? idk if the front and rear o2 sensors through different ones. Just curious

 

p.s. yes they sell other stuff besides spark plugs

He probably replaced the wrong sensor the first time. I bet the down stream sensor was OK. On my car the CEL was for "Rear Cat System Too Rich" and the front sensor was replaced to fix it. I bet he saw "Rear" and though rear o2 sensor. That would be my guess.

Just checked my bill and the code listed for the origional work was P2097 Post Catylist Trim System too Rich Bank 1. I just got my elm scan 5 in the mail and pulled the codes on my car. It is still P2097. Is that the code for the upstream O2 sensor?

Thanks for the Help

Any resolutions to this after 3 years?

 

I had the same code and replaced the downstream as well. My next guess is upstream which costs even more but may be causing it the more I read. Just hoping not the Catalytic...

I had the same code...does the car run a little rough? Mine was surging when I was at constant speeds. Unplug the o2 sensor and drive to see if it goes away? I had to replace the front one and the code went away and the surging disappeared. It was the more expensive sensor. I still have the other one too jic I need it.

FWIW, one of my O2 sensor I got from Carquest Auto parts for $80.00. I have replaced both on my 05, because I replaced the wrong one the first time.

 

I think the other one was like $120.00

 

 

They are easy to replace with the proper $10.00 socket.

I had the same code...does the car run a little rough? Mine was surging when I was at constant speeds. Unplug the o2 sensor and drive to see if it goes away? I had to replace the front one and the code went away and the surging disappeared. It was the more expensive sensor. I still have the other one too jic I need it.

Actually it runs fine until I come to a stop. The RPM drop too low it shudders and either recovers or shuts off.

 

Not sure if there is no air flow or if the car is cutting fuel since this code reads too rich. Hoping replacing the front o2 does it even thought the rear was $90.

 

The front upstream is hard to find. Only one on AAP says it requires two and is Cali. But I don't have Cali emmissions. That messed me up before when I replaced the plug wires.

Well the same upstream on Auto Zone says federal emission Denso 234-9122

that downstream was pain enough to reach. I barely saw the upstream, but not where it connects. This will be fun...

I ordered from rock auto and it was a little over $100. It was a denso one since that is the oem sensor.

They both connect side by side under the intake funnel. Its hard to get a good amount of torque on it just standing in front of it.

He probably replaced the wrong sensor the first time. I bet the down stream sensor was OK. On my car the CEL was for "Rear Cat System Too Rich" and the front sensor was replaced to fix it. I bet he saw "Rear" and though rear o2 sensor. That would be my guess.

 

 

Hoping for a similar experience. Replaced the downstream last week. Code came back and minor surging hesitation never ceased. Ordered upstream on Amazon today for $84.17. Awesome!!! Hoping it heals my problems. Seems my fuel economy is suffering also.

 

Will let you all know what happens...

$84.17 is that for a direct fit ?

$84.17 is that for a direct fit ?

 

 

Yes. This baby right here, but for whatever reason, price just jumped to $100.26

 

[ame=http://www.amazon.com/gp/product/B001F799X6/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1]Denso 234-9120 Oxygen Sensor (Air and Fuel Ratio Sensor) : Amazon.com : Automotive[/ame]

Yes. This baby right here, but for whatever reason, price just jumped to $100.26

 

Denso 234-9120 Oxygen Sensor (Air and Fuel Ratio Sensor) : Amazon.com : Automotive

 

I wonder if it's because all of us "lookie loue's" have driven up the possible demmend for it...

 

 

I found my spare in the shed last weekend, I paid something like $127 at the dealer. May be 137

Hahaha!

 

Doesn't seem right to me, but one of my miserly co-workers suggested cleaning the sensor. Figured I can afford the $85.00 as it will at least be a stepin the right direction.

I'm doing a rear 02 now. What a bitch.

I'm doing a rear 02 now. What a bitch.

 

Try one of these tools with a 3/8 breaker bar. Apply penetrating oil, such as Kroil, the night before.