jeffbeaux83 Posted August 24, 2008 Share Posted August 24, 2008 I have a 2000 corolla CE and recently I dropped from about 40mpg highway to around 32mpg. The car was reading a check engine code and I checked it with a diagnostic computer that said it was a catalytic converter code that had come up twice. Could this be a problem with an o2 sensor or would replacing the catalytic converter bring my mpg's back up. I believe it is not the converter because the car only has 130k on it and this loss of mpg was kind of a sudden thing that coincided with the check engine light coming on. Thanks for any help. Jeff. Quote Link to comment Share on other sites More sharing options...
humanoid Posted August 24, 2008 Share Posted August 24, 2008 What was the exact code that came up? A clogged cat may cause the drop in MPG as does a bad O2 sensor. Quote Link to comment Share on other sites More sharing options...
jeffbeaux83 Posted August 27, 2008 Author Share Posted August 27, 2008 What was the exact code that came up? A clogged cat may cause the drop in MPG as does a bad O2 sensor. Thanks, i think the code was a 420, maybe ch420 i can't exactly remember but it said it was the cat, but i was wondering about the o2, would it be the sensor right behind the cat? thanks again Quote Link to comment Share on other sites More sharing options...
XR2003 Posted September 3, 2008 Share Posted September 3, 2008 2000 Corolla. probably the o2 sensor, but the bad cat is also possible. have it checked with your trusted mechanic or dealership to be certain. Quote Link to comment Share on other sites More sharing options...
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