# O2 sensors 03 jeep wrangler 4.0 **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [October 18, 2008, 5:54pm UTC](https://community.cartalk.com/t/o2-sensors-03-jeep-wrangler-4-0/20879 "2008-10-18T17:54:14Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![03freedom](https://avatars.discourse-cdn.com/v4/letter/0/bb73d2/32.png) [@03freedom](https://community.cartalk.com/u/03freedom)\ **Post date:** [October 18, 2008, 5:54pm UTC](https://community.cartalk.com/t/o2-sensors-03-jeep-wrangler-4-0/20879/1 "2008-10-18T17:54:14Z")
Ok, Here is my question. i had just replaced the 2 o2 sensors that are located after the catalitic converters. does any one know how long it takes to break them in. and yes my check engine light was on. any help would be appreciated ---
**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\ **Post date:** [October 18, 2008, 6:26pm UTC](https://community.cartalk.com/t/o2-sensors-03-jeep-wrangler-4-0/20879/2 "2008-10-18T18:26:52Z")
As far as I know there is no ‘break-in’ period for the sensors. They can degrade over extended time. ---
**Author:** ![03freedom](https://avatars.discourse-cdn.com/v4/letter/0/bb73d2/32.png) [@03freedom](https://community.cartalk.com/u/03freedom)\ **Post date:** [October 18, 2008, 6:41pm UTC](https://community.cartalk.com/t/o2-sensors-03-jeep-wrangler-4-0/20879/3 "2008-10-18T18:41:27Z")
Ok thanks for the help, there both new just put them in 2 hours ago. and about 30 miles and 10 restarts in a half and hour time intervals. so far my check engine light has not come. and thats a plus because it needs to pass inspection and emissions test. ---
**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\ **Post date:** [October 18, 2008, 6:43pm UTC](https://community.cartalk.com/t/o2-sensors-03-jeep-wrangler-4-0/20879/4 "2008-10-18T18:43:59Z")
And is the check engine light on now? You may have to use a scan tool to turn the light off. Disconnecting the battery, on newer model vehicles, may not turn the light off. ---
**Author:** ![03freedom](https://avatars.discourse-cdn.com/v4/letter/0/bb73d2/32.png) [@03freedom](https://community.cartalk.com/u/03freedom)\ **Post date:** [October 18, 2008, 6:47pm UTC](https://community.cartalk.com/t/o2-sensors-03-jeep-wrangler-4-0/20879/5 "2008-10-18T18:47:35Z")
Yes my check engine light is off ,and yes the battery was disconnected during the install. thanks ---
**Author:** ![03freedom](https://avatars.discourse-cdn.com/v4/letter/0/bb73d2/32.png) [@03freedom](https://community.cartalk.com/u/03freedom)\ **Post date:** [October 18, 2008, 6:57pm UTC](https://community.cartalk.com/t/o2-sensors-03-jeep-wrangler-4-0/20879/6 "2008-10-18T18:57:45Z")
I disconnected the battery before and the light would go out for a couple days. but then it would come back again. so i bought a o2 sensor relay switch to see if thats what the problem was. and that did not fix the problem, so i went out and bought 2 new o2 sensors. to see if it would solve the problem so far so good . ---
**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\ **Post date:** [October 18, 2008, 7:17pm UTC](https://community.cartalk.com/t/o2-sensors-03-jeep-wrangler-4-0/20879/7 "2008-10-18T19:17:37Z")
You sound like you are the do-it-yourself type of person. You should consider purchasing a code reader/scanner for the OBD-2 system. Then you can check what is going on with the system. Actron and Equus make some nice ones along with other manufacturers. ---
**Author:** ![03freedom](https://avatars.discourse-cdn.com/v4/letter/0/bb73d2/32.png) [@03freedom](https://community.cartalk.com/u/03freedom)\ **Post date:** [October 18, 2008, 7:30pm UTC](https://community.cartalk.com/t/o2-sensors-03-jeep-wrangler-4-0/20879/8 "2008-10-18T19:30:04Z")
Yes i like to do it myself, it puts some of that money that you would pay to have it fixed at a shop. and i enjoy the time working on the vehicle. at the same time learning something new at the same time. seems like the problem is fixed for the time being fingers crossed. and i would like to thank cougar and hellokit for your time and information. thanks, oh and i will keep you up to date if the problem is fixed for good.