# Do I need a working O2 sensor in my car? **URL:** \ **Category:** Factual Questions\ **Created:** [March 19, 2008, 11:23pm UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004 "2008-03-19T23:23:10Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Love\_Rhombus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/love_rhombus/32/10694_2.png) [@Love\_Rhombus](https://boards.straightdope.com/u/Love_Rhombus)\ **Post date:** [March 19, 2008, 11:23pm UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/1 "2008-03-19T23:23:10Z")
A few days ago my check engine light comes on, so I make an appointment. He hooks it up to the computer and tells me that my O2 sensor is out of whack and will eventually stop working. I should get it replaced. Then he quotes me an ugly price. My question is, can I just not get a new one and drive around with this thing not working to save money? I don’t do much driving. Or is this a critical bit of equipment? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [March 19, 2008, 11:36pm UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/2 "2008-03-19T23:36:07Z")
We just went over this, but of course the search function is broken… The short answer is: **yes** , get it fixed. ---
**Author:** ![Love\_Rhombus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/love_rhombus/32/10694_2.png) [@Love\_Rhombus](https://boards.straightdope.com/u/Love_Rhombus)\ **Post date:** [March 19, 2008, 11:39pm UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/3 "2008-03-19T23:39:15Z")
But but but…my money! :eek: My beautiful money! I sleep with it in my pants, I love it so! I don’t think it was exactly the same question (if i read the right one) but I’m just being pedantic. I’ll go get it replaced. _grumble_ stupid person stealing my question_grumble_ ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [March 19, 2008, 11:45pm UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/4 "2008-03-19T23:45:39Z")
Replacing an O2 sensor is one of the easiest jobs to do on a car\*. Shouldn’t cost more than $100. Find a “shade tree” mechanic to do it if you can’t do it yourself. \*Unless your vehicle has it installed in some obnoxious location. ---
**Author:** ![Love\_Rhombus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/love_rhombus/32/10694_2.png) [@Love\_Rhombus](https://boards.straightdope.com/u/Love_Rhombus)\ **Post date:** [March 19, 2008, 11:47pm UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/5 "2008-03-19T23:47:02Z")
[QUOTE=beowulff] Replacing an O2 sensor is one of the easiest jobs to do on a car\*. Shouldn’t cost more than $100. Find a “shade tree” mechanic to do it if you can’t do it yourself. \*Unless your vehicle has it installed in some obnoxious location. [/QUOTE] It’s a Saab, and apparently they’re more expensive. He asked 300+. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [March 20, 2008, 12:19am UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/6 "2008-03-20T00:19:43Z")
Well, putting the job off for a short while probably won’t wreck your engine, but it can lead to burned valves or carbon buildup, and it can ruin your catalytic converter (which is probably _ **really** _ expensive). Not to mention the extra pollution. I’d shop around a bit. ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [March 20, 2008, 12:23am UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/7 "2008-03-20T00:23:12Z")
I’ll take “Obnoxious Locations” for $400, Alex. ---
**Author:** ![Bob55](https://avatars.discourse-cdn.com/v4/letter/b/e9c0ed/32.png) [@Bob55](https://boards.straightdope.com/u/Bob55)\ **Post date:** [March 20, 2008, 12:50am UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/8 "2008-03-20T00:50:29Z")
I said this in another thread and made some auto guys angry, but from what I’ve been told you really don’t need to worry too much about it _if_ it’s the downstream sensor. It’s the upstream sensor that is most important, but either way they’re both about $50 from online websites and evidently easy to install…although I’ve gone now several years without replacing mine and have experienced zero decrease in mileage. I’m sure I’ll give in and replace it eventually though. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 20, 2008, 2:46am UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/9 "2008-03-20T02:46:00Z")
[QUOTE=Bob55] I said this in another thread and made some auto guys angry, but from what I’ve been told you really don’t need to worry too much about it _if_ it’s the downstream sensor. It’s the upstream sensor that is most important, but either way they’re both about $50 from online websites and evidently easy to install…although I’ve gone now several years without replacing mine and have experienced zero decrease in mileage. I’m sure I’ll give in and replace it eventually though. [/QUOTE] And you were told by people that do this stuff for a living that you are incorrect in this assumption. Just because you got away with something, does not mean it is safe or a good idea. **Love Rhombus** You didn’t say what year or model SAAB we are discussing so I can only guess. I looked up prices on O2 sensors for several years and models. They ranged from $228- $292 for the front sensor. Some of the rears were as expensive, some were less. ETA: these are parts only prices, not parts and labor. ---
**Author:** ![Bob55](https://avatars.discourse-cdn.com/v4/letter/b/e9c0ed/32.png) [@Bob55](https://boards.straightdope.com/u/Bob55)\ **Post date:** [March 20, 2008, 2:53am UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/10 "2008-03-20T02:53:45Z")
[QUOTE=Rick] And you were told by people that do this stuff for a living that you are incorrect in this assumption. Just because you got away with something, does not mean it is safe or a good idea. [/QUOTE] I never implied that, I only gave the input I had from credible sources on the subject. As I said in the other thread I was told this by people that do this stuff for a living as well. But I’m sure the more you’re into an industry the more you follow the rules - I make sure to take every antibiotic I’m ever prescribed because I know the side effects if I stop taking them early, but I’d say most people not in science just stop taking them when they feel better. So yes, you’re right in that you _shouldn’t_ ignore the warning signs or the advice of people like you who actually know what they are talking about, but I am just telling the OP the experiences I’ve had…if he doesn’t have $300 to spend I see no problem with waiting a little bit to fix the issue. ---
**Author:** ![Love\_Rhombus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/love_rhombus/32/10694_2.png) [@Love\_Rhombus](https://boards.straightdope.com/u/Love_Rhombus)\ **Post date:** [March 20, 2008, 3:09am UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/11 "2008-03-20T03:09:52Z")
[QUOTE=Rick] **Love Rhombus** You didn’t say what year or model SAAB we are discussing so I can only guess. I looked up prices on O2 sensors for several years and models. They ranged from $228- $292 for the front sensor. Some of the rears were as expensive, some were less. ETA: these are parts only prices, not parts and labor. [/QUOTE] A 93 Saab (why would you make the model a number? Seems confusing). Yeah, labor was added to put the part in and for plugging it into the computer I guess. And I do have the money, it will just make things annoyingly tight when I thought they were good. Thanks for the answers all, you definitally tipped me away from just leaving it broken, especially since it occurs to me that if something else goes wrong while it is messed up, I’d have no little warning light to tell me. ---
**Author:** ![suranyi](https://avatars.discourse-cdn.com/v4/letter/s/e36b37/32.png) [@suranyi](https://boards.straightdope.com/u/suranyi)\ **Post date:** [March 20, 2008, 5:27am UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/12 "2008-03-20T05:27:05Z")
If you live in California I don’t think you can pass the smog test if this isn’t fixed. Ed ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [March 20, 2008, 5:39am UTC](https://boards.straightdope.com/t/do-i-need-a-working-o2-sensor-in-my-car/442004/13 "2008-03-20T05:39:51Z")
[QUOTE=suranyi] If you live in California I don’t think you can pass the smog test if this isn’t fixed. Ed [/QUOTE] Trust me, you can’t.