# Check engine light **URL:** \ **Category:** PittSpeed Automotive\ **Created:** [February 17, 2004, 9:15am UTC](https://forums.speedlife.net/t/check-engine-light/164164 "2004-02-17T09:15:05Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![grandamld9](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@grandamld9](https://forums.speedlife.net/u/grandamld9)\ **Post date:** [February 17, 2004, 9:15am UTC](https://forums.speedlife.net/t/check-engine-light/164164/1 "2004-02-17T09:15:05Z")
I went to autozone and they hooked up the scan tool to my car to see what code i was throughing, and it threw a P0420, it says something about the catalyst system in bank 1 is below threshold. Im thinking its an O2 sensor, but is bank 1 before or after the cat? Or could it be another problem. I have a 97 grandam with the 2.4L engine. ---
**Author:** ![Pewter](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/pewter/32/5936_2.png) [@Pewter](https://forums.speedlife.net/u/Pewter)\ **Post date:** [February 17, 2004, 9:21am UTC](https://forums.speedlife.net/t/check-engine-light/164164/2 "2004-02-17T09:21:49Z")
bank 1 is in front of cat on single exhaust!!!bank 1 which sensor? ---
**Author:** ![Pewter](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/pewter/32/5936_2.png) [@Pewter](https://forums.speedlife.net/u/Pewter)\ **Post date:** [February 17, 2004, 9:23am UTC](https://forums.speedlife.net/t/check-engine-light/164164/3 "2004-02-17T09:23:39Z")
they have bank one with sensor 1 & 2 duals have bank 1 & bank 2,sensor 2 is always the one after that cat!!! ---
**Author:** ![grandamld9](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@grandamld9](https://forums.speedlife.net/u/grandamld9)\ **Post date:** [February 17, 2004, 9:28am UTC](https://forums.speedlife.net/t/check-engine-light/164164/4 "2004-02-17T09:28:12Z")
this is what the little troubleshooting thing says “The PCM determined that the catalyst system effivinvy for bank 1 is below threshould for the current engine operating conditions.(bank 1 identifies the location of the cylinder #1, while bank 2 identifies the cylinder on the opposite bank)” ---
**Author:** ![Pewter](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/pewter/32/5936_2.png) [@Pewter](https://forums.speedlife.net/u/Pewter)\ **Post date:** [February 17, 2004, 9:34am UTC](https://forums.speedlife.net/t/check-engine-light/164164/5 "2004-02-17T09:34:51Z")
> _Originally posted by 97GrandAMLD9_ > **this is what the little troubleshooting thing says “The PCM determined that the catalyst system effivinvy for bank 1 is below threshould for the current engine operating conditions.(bank 1 identifies the location of the cylinder #1, while bank 2 identifies the cylinder on the opposite bank)”** > 😕 call me 1-800-680-2959 brian! ---
**Author:** ![Sight\_N\_Sound](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/sight_n_sound/32/5950_2.png) [@Sight\_N\_Sound](https://forums.speedlife.net/u/Sight_N_Sound)\ **Post date:** [February 17, 2004, 9:40am UTC](https://forums.speedlife.net/t/check-engine-light/164164/6 "2004-02-17T09:40:56Z")
> _Originally posted by Pewterss_ > **😕 call me 1-800-680-2959 brian!** Is that something like when Prince went by that fucked up Sign for his name? ---
**Author:** ![Pewter](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/pewter/32/5936_2.png) [@Pewter](https://forums.speedlife.net/u/Pewter)\ **Post date:** [February 17, 2004, 9:41am UTC](https://forums.speedlife.net/t/check-engine-light/164164/7 "2004-02-17T09:41:50Z")
> _Originally posted by Sight N Sound_ > **Is that something like when Prince went by that fucked up Sign for his name?** > 😕 draw me a pic!!! ---
**Author:** ![Quik](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/quik/32/5979_2.png) [@Quik](https://forums.speedlife.net/u/Quik)\ **Post date:** [February 17, 2004, 12:15pm UTC](https://forums.speedlife.net/t/check-engine-light/164164/8 "2004-02-17T12:15:25Z")
is it running rich, i got the engine light on and i have a bad O2 sensor ---
**Author:** ![grandamld9](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@grandamld9](https://forums.speedlife.net/u/grandamld9)\ **Post date:** [February 17, 2004, 12:32pm UTC](https://forums.speedlife.net/t/check-engine-light/164164/9 "2004-02-17T12:32:17Z")
> _Originally posted by Quik_ > **is it running rich, i got the engine light on and i have a bad O2 > sensor** IDK i havent seen any black smoke come out of the exhuast to indicate that, but i am getting about 19mpg in the city. Also i replaced the O2 censor on the downpipe/exhuast manifold i had the check engine light turned off and it came back on. so idk ---
**Author:** ![Quik](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/quik/32/5979_2.png) [@Quik](https://forums.speedlife.net/u/Quik)\ **Post date:** [February 17, 2004, 5:27pm UTC](https://forums.speedlife.net/t/check-engine-light/164164/10 "2004-02-17T17:27:28Z")
the O2 that is bad on my Z24 is the one after the cat, check that one out ---
**Author:** ![grandamld9](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@grandamld9](https://forums.speedlife.net/u/grandamld9)\ **Post date:** [February 19, 2004, 1:25pm UTC](https://forums.speedlife.net/t/check-engine-light/164164/11 "2004-02-19T13:25:36Z")
i went to auto zone agian and got the code its a P420, and the guy said it could be that the cat is bad, there is a misfire, or that there is a large vacum leak. anyone have any ideas? ---
**Author:** ![grandamld9](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@grandamld9](https://forums.speedlife.net/u/grandamld9)\ **Post date:** [February 19, 2004, 4:44pm UTC](https://forums.speedlife.net/t/check-engine-light/164164/12 "2004-02-19T16:44:57Z")
how would i check to see if it is one of the three options? ---
**Author:** ![Sight\_N\_Sound](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/sight_n_sound/32/5950_2.png) [@Sight\_N\_Sound](https://forums.speedlife.net/u/Sight_N_Sound)\ **Post date:** [February 19, 2004, 4:46pm UTC](https://forums.speedlife.net/t/check-engine-light/164164/13 "2004-02-19T16:46:36Z")
Take it to a dealer… ---
**Author:** ![Quik](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/quik/32/5979_2.png) [@Quik](https://forums.speedlife.net/u/Quik)\ **Post date:** [February 19, 2004, 5:43pm UTC](https://forums.speedlife.net/t/check-engine-light/164164/14 "2004-02-19T17:43:19Z")
its probably the cat ---
**Author:** ![blackfive-o](https://avatars.discourse-cdn.com/v4/letter/b/3e96dc/32.png) [@blackfive-o](https://forums.speedlife.net/u/blackfive-o)\ **Post date:** [February 20, 2004, 5:00am UTC](https://forums.speedlife.net/t/check-engine-light/164164/15 "2004-02-20T05:00:19Z")
Make sure the gas cap is on tight. Wifes 98 Trans Sport lite came on, I called to make an appointment to have it looked at, they said first make sure the cap is on tight. Well, did that and shortly the light went off. No shit! ---
**Author:** ![imported\_Sleeper](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/imported_sleeper/32/5939_2.png) [@imported\_Sleeper](https://forums.speedlife.net/u/imported_Sleeper)\ **Post date:** [February 22, 2004, 9:46am UTC](https://forums.speedlife.net/t/check-engine-light/164164/16 "2004-02-22T09:46:43Z")
It,s a bad cat,when i put my d/p on my gp the code would come up all the time cause there is no cat on it.i would have to say that is your prob.