A few weeks ago, my check engine light came on. I got myself to Autozone, had the codes scanned, and found out that my upstream oxygen sensor is on the fritz. (The person at Autozone told me that it was “bank 1, sensor 1,” and that I have four oxygen sensors; however, extensive examination of my undercarriage revealed that I only have two oxygen sensors – one upstream, one downstream.)
Autozone wanted $313 or so for the sensor, but I found one on Amazon.com for less than $150. After some more research (thanks, Matthew’s Volvo site!), I found that the procedure for replacing an oxygen sensor is as follows:
- Put car up on car ramps;
- Once engine is cool, douse oxygen sensor in PB Blaster or WD-40 and wait about ten minutes;
- Using special oxygen sensor wrench, remove oxygen sensor;
- Unplug other end of oxygen sensor (note: in Volvo V70s, the upstream sensor has a black plug and the downstream sensor has a grey plug);
- Install new sensor.
Bizarrely, it was almost that easy. Mr. Velociraptor’s dad has car ramps and an oxygen sensor wrench, so we went to his place for the repair. (Confession time: when I described the exhaust system, I said something about the engine leading to a metal piece that is the ‘size and shape of a doughnut.’ Mr. Velociraptor and his father were entirely confused until the latter said, “You mean a flange?” I also described the catalytic converter as ‘something that looks like a giant metal slug.’ For those trying this repair at home, the upstream sensor is right near the doughnut, and the downstream sensor is plugged right into the giant metal slug.)
It was pretty easy to get the sensor off: I crawled under the car, put the wrench on the sensor, fitted a small ratcheting handle to it (there wasn’t much room for a large one), and pulled gently, then not-so-gently, until it became loose. Mr. Velociraptor did the rest of it. The challenging part was removing the clip. I tried for ten minutes and was useless. Mr. Velociraptor tried and couldn’t figure it out. His dad loosened part of it. Finally, with my boyfriend under my car and myself over it, I looked down and said, “Hey, that metal tube comes off really easily, doesn’t it?” Here’s the metal tube in question:
and another shot of it, where you can sort of see the plugs for the oxygen sensors, tucked away in the upper right side:
From our experience replacing the ABS module, that metal pipe is ridiculously easy to remove (you just pull it off at each end and then, if you’re smart like my boyfriend, lay it on the hood in the exact same position that it goes into the car). Once that was out of the way, the plugs were much easier to access. For those following along at home, take that sucker off and you can get to the plugs via the top of the car.
The oxygen sensor came with unlabeled copper grease; some internet research showed that it’s anti-seize that should go on the threads of the sensor for easy removal next time (oxygen sensor life expectancy: 100,000 miles; Volvo life expectancy: until you’re an idiot and wreck it in an accident). I got the honour of crawling under the car with the oxygen sensor and putting it back in; Mr. Veliciraptor plugged the other end in. Don’t do it in reverse order or you’ll end up with a tangled line. The CEL even reset itself after a few trips.
Okay, so maybe “girl power” isn’t quite the right term, given that it was definitely a team effort. But I’m still pretty darn proud of myself for figuring out the problem, ordering the part, and doing a decent chunk of the replacement.