1998 Cadillac Deville check gas cap

1998 CADILLAC DEVILLE
186,000 MILES • 6 CYL • FWD • AUTOMATIC
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2009 TRENCHING
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  • 1 POST
error message "check gas cap" "service engine soon". I have replaced gas cap and still get the message.
Oct 4, 2009 at 9:51 PM
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FACTORYJACK
  • ✓ASE Certified Mechanic
  • 4,159 POSTS
  • ASE Certified Mechanic
The evap system(fuel) could have a large leak, it assumes it could be a fuel cap loose or off. Possibilities include the fuel tank pressure sensor, faulty vent solenoid or purge solenoid, or a physical leak somewhere in the fuel system. Periodically the ECM commands the vent solenoid closed, cycles the purge solenoid to apply vaccum to the fuel system, and monitors the rate of decay. If the decay is deemed rapid, it will set a large leak fault.
Oct 6, 2009 at 12:43 AM
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