which o2 sensor is more likely to fail

2000 KIA SEPHIA
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RIEBED
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Hi My question relates to o2 sensors- I have a post cat o2 sensor and a precat o2 sensor, which one gets the most wear(use) and usually goes out first? gets expensive to replace
Nov 13, 2011 at 7:44 PM
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JJIMENEZ8891
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They both I would say get wear,Kind of a odd question for what reason do you ask? possibly the rear may recieve more heat depending how close to th Cat it is, But The Pre Cat typically has more of a use. also in some vehicles known as the fuel ratio sensor it has a bigger job I guess you can say.
Nov 13, 2011 at 7:51 PM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,240 POSTS
He is correct... the pre cat sensor is responsible for fuel mixture. However, they both work the same amount. For some reason, however, the post cat sensor seems to need replacement more often.
Nov 13, 2011 at 9:21 PM
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