Replaced O2 sensor but engine light stays on
 

2004 Outlander AWD - 140k miles


My check engine light was on due to a faulty O2 Sensor in Bank 1 Sensor 2. Since the sensor was $150 at autozone, I replaced the sensor with an aftermarket brand I found on ebay for $40. Then, I disconnected the negative terminal to the battery to reset the check engine light. Once I start the car, the light does not reappear until after I have been driving for 10 min or so. I had the error read again and it still says o2 sensor in bank 1 sensor 2. What did I do wrong? Did I shoot myself in the foot by getting a cheap part on ebay?


I replaced the upstream sensor right before the catalytic converter. Sure hope I didn't replace the wrong one. : /
Thanks.
Dan

did you actively clear the check engine alerts?

I certainly wouldn't get a cheap-o off of ebay. There are ways of getting prices down online. Retailmenot.com has codes for some parts stores. I used Advance Auto Parts where they have some codes up to 40% off.

Here's what Autopartswherehouse.com says about Oxygen Sensor numbering:
- Bank 1 is located at the side of the engine where cylinder #1 is found as well.
- Bank 2 is on the opposite side of Bank 1.
- On a 4-cylinder engine, there is only one bank that's called Bank 1.
- Sensor 1 is the upstream sensor located before the catalytic converter.
- Sensor 2 is the downstream sensor located after the catalytic converter.

Thanks for responding.
Guy at autozone told me it was the upstream one and even referred me to a diagram. ugh. At least I know the answer to my problem now. Live and Learn. I'll check out the sites. Thanks again.

Most of the parts on eBay are replicas/defective parts. I would suggest buying from authorized places.

playing with numbers, I got Advance down to $152, AutoZone down to $160, and RockAuto.com down to $135 for the Bosch downstream AWD.

Cool. I have a O'reily, Advance, and Autozone near me. I'll compare against the 3 and go with one of them. Thanks guys.