# 02 sensor **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [August 30, 2014, 4:38am UTC](https://community.cartalk.com/t/02-sensor/86886 "2014-08-30T04:38:13Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![amendoz1](https://avatars.discourse-cdn.com/v4/letter/a/9d8465/32.png) [@amendoz1](https://community.cartalk.com/u/amendoz1)\ **Post date:** [August 30, 2014, 4:38am UTC](https://community.cartalk.com/t/02-sensor/86886/1 "2014-08-30T04:38:13Z")
I have an 2006 honda accord v6 couple model. It has 165k miles and lately I’ve noticed I’m getting terrible gas mileage. The car passed a smog check in southern California. I’m considering on changing the 02 sensors. Does any knowledge if it’s okay or if there are any issues with using non dealer 02 sensors like Bosch? Is there a particular sensor that I need to change? This vehicle has 3 sensor and I’m not sure if I need to change all 3 or if I can just one in particular. I also had the timing belt changed but the car starts and runs fine so I didn’t think it’s something to do with the timing. Anyone the exact specs of when to change 02 sensor? ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [August 30, 2014, 4:48am UTC](https://community.cartalk.com/t/02-sensor/86886/2 "2014-08-30T04:48:53Z")
I’m assuming there is just one cat and tailpipe. There are probably two proximate sensors, one in each of the two exhaust paths, and one sensor after the cat. If mpg is a concern, that would more likely be one or both of the proximate sensors. But I doubt that’s the problem. Esp if you passed CA smog, as it would show up in spades in the HC test parameter. Folks here usually recommend to use the manufacturer’s recommendation for brand when replacing O2 sensors. For my Corolla I used Denso. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [August 30, 2014, 4:50am UTC](https://community.cartalk.com/t/02-sensor/86886/3 "2014-08-30T04:50:35Z")
Before doing anything drastic, check the ECM codes even if the check engine light isn’t on. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [August 30, 2014, 4:51am UTC](https://community.cartalk.com/t/02-sensor/86886/4 "2014-08-30T04:51:24Z")
Is the Check Engine light on? If not, there’s not a problem with the O2 sensor(s) Tester ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [August 30, 2014, 5:17am UTC](https://community.cartalk.com/t/02-sensor/86886/5 "2014-08-30T05:17:35Z")
There could be some pending codes ---
**Author:** ![knfenimore](https://avatars.discourse-cdn.com/v4/letter/k/9fc348/32.png) [@knfenimore](https://community.cartalk.com/u/knfenimore)\ **Post date:** [August 30, 2014, 5:42am UTC](https://community.cartalk.com/t/02-sensor/86886/6 "2014-08-30T05:42:16Z")
O2 sensors can get lazy and not throw a code. There’s a big article on testing lazy o2 sensors on Hondas, but you need an oscope. [http://www.motor.com/article.asp?article\_ID=1816](http://www.motor.com/article.asp?article_ID=1816) ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [August 30, 2014, 5:51am UTC](https://community.cartalk.com/t/02-sensor/86886/7 "2014-08-30T05:51:15Z")
How are you checking the fuel mileage; the gallons to fill vs miles driven method? How’s the tire pressure? One low tire can kill fuel mileage.