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1997 Seville STS
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14 Posts
Discussion Starter · #1 ·
I have a 97 STS that I just did the head bolt insert and top end gaket repair to. I have replaced both exhaust manifold O2 sensors and now when I clear the codes on the MIL it stays gone for about 15 miles but then the SES pops up with all O2 codes. I am hoping that someone can help. I have a great deal of time, money and effort into this and all I have to do is make the codes go away so that the SES will stay off so that I can smog and tab it. Thank you to anyone who can help!
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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72,798 Posts
99% of the time O2 sensor codes and messages are set due to either vacuum or fuel problems: fuel/air mixture faults. There should be other Trouble Codes associated with your O2 sensor indications.

Do a systematic vacuum leak diagnosis as well as fuel injector and pressure regulator checks.
 

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1997 Seville STS
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14 Posts
Discussion Starter · #3 ·
Thank you for the response. I checked every vacuum connector and it is tight and sealed, no variance at all. What do I need to do check the feul pressure besides a tester?
 
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