The check engine light in my 2004 Matrix came on yesterday morning. I was kinda alarmed, so I stopped at an Advance Auto Parts. They helpfully checked the code in the OBD2 and turned out it was the first oxigen sensor.

I picked up a universal Bosch oxigen sensor (the OE one was not in stock and $30 more expensive). Last night I got it installed – took me about an hour because I didn’t cut the wires long enough, and the PosiLock wire splicing that was included in the kit was a pain to get right.

After installing it, I started the engine – the check engine light was still on. I was hoping it will turn itself off while driving to work this morning, but after about 10 minutes it didn’t. So I called the store and they asked if I did reset the computer (remove one of the battery connectors, preferrably the negative, for 3-5 minutes).

That seems to have done the trick – funny this step was not included in the directions.

Total cost: $75 parts, 1 hour labor.