# 2004 Mitsubishi Endeavor P0421

**URL:** <https://community.cartalk.com/t/2004-mitsubishi-endeavor-p0421/134655>\
**Category:** Maintenance/Repairs\
**Tags:** endeavor, mitsubishi\
**Created:** [February 14, 2019, 10:55pm UTC](https://community.cartalk.com/t/2004-mitsubishi-endeavor-p0421/134655 "2019-02-14T22:55:18Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![David16](https://avatars.discourse-cdn.com/v4/letter/d/f4b2a3/32.png) [@David16](https://community.cartalk.com/u/David16)\
**Post date:** [February 14, 2019, 10:55pm UTC](https://community.cartalk.com/t/2004-mitsubishi-endeavor-p0421/134655/1 "2019-02-14T22:55:18Z")

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My check engine light has been coming off and on for 2 years. Code P0421. Had the 02 sensors changed last week, light went off. Drove for 4 days, light came back on (stayed on) for the past 2 days. Light went off this morning, chanced DEQ because tags expire in a week. IT PASSED! What gives? Hiccup in my cars system? Miracle?

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**Author:** ![tcmichnorth](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tcmichnorth/32/25126_2.png) [@tcmichnorth](https://community.cartalk.com/u/tcmichnorth)\
**Post date:** [February 14, 2019, 11:28pm UTC](https://community.cartalk.com/t/2004-mitsubishi-endeavor-p0421/134655/2 "2019-02-14T23:28:11Z")

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Should have the catylitic converter checked. Could be starting to malfunction.