# 2004 Toyota Tacoma - Should I replace O2 sensor? **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** engines, toyota\ **Created:** [September 28, 2024, 9:18pm UTC](https://community.cartalk.com/t/2004-toyota-tacoma-should-i-replace-o2-sensor/197104 "2024-09-28T21:18:49Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Bill47](https://avatars.discourse-cdn.com/v4/letter/b/90db22/32.png) [@Bill47](https://community.cartalk.com/u/Bill47)\ **Post date:** [September 28, 2024, 9:18pm UTC](https://community.cartalk.com/t/2004-toyota-tacoma-should-i-replace-o2-sensor/197104/1 "2024-09-28T21:18:49Z")
oxygen sensor 2004 Tacoma is it worth replacing? ---
**Author:** ![weekend-warrior](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/weekend-warrior/32/26122_2.png) [@weekend-warrior](https://community.cartalk.com/u/weekend-warrior)\ **Post date:** [September 28, 2024, 9:23pm UTC](https://community.cartalk.com/t/2004-toyota-tacoma-should-i-replace-o2-sensor/197104/2 "2024-09-28T21:23:00Z")
[Toyota Tacoma bad O2 sensor symptoms, causes, and diagnosis (wheelsjoint.com)](https://www.wheelsjoint.com/toyota-tacoma-bad-o2-sensor-symptoms-causes-and-diagnosis/#:~:text=According%20to%20EPA%2C%20replacing%20a%20bad%20oxygen%20sensor,vehicle%20has%20racked%20up%20more%20than%20100%2C000%20miles.) ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [September 28, 2024, 10:24pm UTC](https://community.cartalk.com/t/2004-toyota-tacoma-should-i-replace-o2-sensor/197104/3 "2024-09-28T22:24:22Z")
> [@Bill47](#): > > oxygen sensor 2004 Tacoma is it worth replacing? Why are you asking?? CEL/MIL light on with a Code?? Preventive maintenance?? Running issue?? ---
**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:** [September 29, 2024, 6:14pm UTC](https://community.cartalk.com/t/2004-toyota-tacoma-should-i-replace-o2-sensor/197104/4 "2024-09-29T18:14:47Z")
> [@Bill47](#): > > oxygen sensor 2004 Tacoma is it worth replacing? The engine management computer uses the output signals from the O2 sensors to set the optimum air/fuel ratio. The engine will never run correctly with a faulty O2 sensor; however O2 sensors are pretty robust gadgets, so it is possible this is actually a misdiagnosis. Suggest you explain why you or your shop think the O2 sensor is the problem? ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [September 29, 2024, 6:20pm UTC](https://community.cartalk.com/t/2004-toyota-tacoma-should-i-replace-o2-sensor/197104/5 "2024-09-29T18:20:41Z")
Depends on the overall condition of your truck. Is the frame rusted through? Does the engine need rebuilding? Is the transmission shot? ---
**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:** [September 29, 2024, 7:20pm UTC](https://community.cartalk.com/t/2004-toyota-tacoma-should-i-replace-o2-sensor/197104/6 "2024-09-29T19:20:18Z")
> [@Purebred](#): > > Depends on the overall condition of your truck. Good point. OP, are you asking about the wisdom of replacing the truck, or about replacing the O2 sensor? ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [September 30, 2024, 9:59pm UTC](https://community.cartalk.com/t/2004-toyota-tacoma-should-i-replace-o2-sensor/197104/7 "2024-09-30T21:59:39Z")
Which O2 sensor? The one past the catalytic converter? Or the engine side, upstream, sensor? The engine will not run correctly with a bad upstream sensor so Yes. The downstream sensor reads whether your catalytic converter still works. The truck will run OK but the check engine light will always be on and you will fail any emissions tests if your state has them.