1999 Grand Marquis Check Engine Light

Asked by May 25, 2019 at 01:35 PM about the 1999 Mercury Grand Marquis

Question type: Maintenance & Repair

Check engine light has been on for
two years. I live in California and it’s
time to smog my car. Drives with no

When scanned, the following code
appears: P0455 - evaporative
emission system leak detected (gross
leak/no flow)

I got a new gas cap. Did not work.
Does anyone know what else it could
be? I have no clue what step I should
take next..

Please help!!!

3 Answers


This is a leak in the EVAP system. could be a vent line, purge valve or a defective charcoal canister. It has to be fixed to pass smog.

2 people found this helpful.

The people who do the Smog check will usually tell you what needs to be replaced. Just try to due this well a head of time so your tags don't Expire.


Yes, they'll tell you that you failed due to a defect in the EVAP system. They can't tell you anything more than the code reader does. But you already know this. Why put yourself on their FAILED radar if you don't have to; they'll take the next decade or so sending you to a test only station because you'll be suspected of cheating.

1 people found this helpful.

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