# 2000 Jeep Cherokee Check Engine Light **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** cherokee, jeep\ **Created:** [April 15, 2010, 5:10pm UTC](https://community.cartalk.com/t/2000-jeep-cherokee-check-engine-light/47499 "2010-04-15T17:10:09Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Jguzman1326](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/jguzman1326/32/1746_2.png) [@Jguzman1326](https://community.cartalk.com/u/Jguzman1326)\ **Post date:** [April 15, 2010, 5:10pm UTC](https://community.cartalk.com/t/2000-jeep-cherokee-check-engine-light/47499/1 "2010-04-15T17:10:09Z")
I had the vehicle tested and was told it was the O2 Sensor. I replaced the one in front of the cat converter and the light went off for about a week. It came back on again yesterday and I am wondering if I need to change the other sensor or if it could be another problem? Thanks for your responses. Goose ---
**Author:** ![common-sense-answer](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/common-sense-answer/32/716_2.png) [@common-sense-answer](https://community.cartalk.com/u/common-sense-answer)\ **Post date:** [April 15, 2010, 5:19pm UTC](https://community.cartalk.com/t/2000-jeep-cherokee-check-engine-light/47499/2 "2010-04-15T17:19:57Z")
1 - Maybe. 2 - Yes. You Are “Throwing Parts” At It. The CEL & The Codes That Set It Tell Which Circuit / System Experienced The Fault, Not Necessarily Which Part(s). Your car can give one of many or many O2 sensor fault codes. What specific code(s) are you chasing? CSA ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [April 15, 2010, 5:50pm UTC](https://community.cartalk.com/t/2000-jeep-cherokee-check-engine-light/47499/3 "2010-04-15T17:50:35Z")
So who told you the O2 was the problem; a counter guy at AutoZone or something? The O2s get blamed for a lot of things. The fact that you may have an O2 related code does not mean the O2 is the problem. This is where the diagnostics start. ---
**Author:** ![Jguzman1326](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/jguzman1326/32/1746_2.png) [@Jguzman1326](https://community.cartalk.com/u/Jguzman1326)\ **Post date:** [April 25, 2010, 9:35pm UTC](https://community.cartalk.com/t/2000-jeep-cherokee-check-engine-light/47499/4 "2010-04-25T21:35:17Z")
[http://www.obd-codes.com/p0138](http://www.obd-codes.com/p0138) This is my error code. I am figuring that I should change the lower O2 sensor at this point. Everything else on the vehicle looks solid. btw, Thank you both for your responses! ---
**Author:** ![galant](https://avatars.discourse-cdn.com/v4/letter/g/77aa72/32.png) [@galant](https://community.cartalk.com/u/galant)\ **Post date:** [April 25, 2010, 9:49pm UTC](https://community.cartalk.com/t/2000-jeep-cherokee-check-engine-light/47499/5 "2010-04-25T21:49:40Z")
From your own source: A code P0138 may mean that one or more of the following has happened: ``` * Faulty O2 sensor * Short to battery voltage in O2 sensor signal circuit * High fuel pressure (not as likely) ``` Now if this is a DIY project and you are saving a ton on labor it might be worth changing the other sensor, otherwise if a shop has done the work take the car back and ask them to fix it properly. ---
**Author:** ![galant](https://avatars.discourse-cdn.com/v4/letter/g/77aa72/32.png) [@galant](https://community.cartalk.com/u/galant)\ **Post date:** [April 25, 2010, 9:50pm UTC](https://community.cartalk.com/t/2000-jeep-cherokee-check-engine-light/47499/6 "2010-04-25T21:50:13Z")
Also forgot to ask, is the code still the same? ---
**Author:** ![Jguzman1326](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/jguzman1326/32/1746_2.png) [@Jguzman1326](https://community.cartalk.com/u/Jguzman1326)\ **Post date:** [April 26, 2010, 3:31pm UTC](https://community.cartalk.com/t/2000-jeep-cherokee-check-engine-light/47499/7 "2010-04-26T15:31:04Z")
Hey again, I replaced upper O2 sensor myself, not paying a place to do a five minute job for me. The code is still the same though. I have to climb under there and change the second one. They are not expensive and might take care of it. I was also told that a bad gas cap has a very small chance of being the problem as well. I figure once it stops raining here I will replace both items and then see where I need to go from there. This thing has 122k on it. They were due anyways. But suggestions if those don’t care of it are helpful. If it is a short, I have checked the battery cables and they seem fine. Do I take it to a mechanic or is there something else I should be checking?