1998 Cadillac Seville Codes 0400 0303 One Ranndom Misfire Other Evap Emmision

1998 CADILLAC SEVILLE
174,000 MILES
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i have codes 0400 and 0303 one is a ranndom misfire and the other is a evap emmision control what exactly could be the problem on both codes do i need my spark plugs changed out and could it be my 0 2 sensor i need a little help here
Nov 2, 2012 at 12:41 PM
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ASEMASTER6371
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codes never identify bad parts, just failed systems.

the missfire could be plug, wire, cap or rotor, injector, compression.


the evap needs to be smoke tested for leaks and all solenoids checked

Roy
Nov 2, 2012 at 12:43 PM
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