Tighten Gas Cap message, followed by the check engine light.

SOURCE: 2002 monte carlo EVAP problem continues.

did you try a vent solenoid? this is located behind left rear wheel in fender.

SOURCE: engine light stays o n my 2006 impala

you may have to reset the engine light. These cars are all computerized. Call the dealership and tell them that you had to replace the gas cap as it was faulty and caused your check engine light to come on. Ask them if they can reset the "computer" or if they can tell you how to do it (if that is possible).

Don't know if that will work, but my dad has been in the car business for over 35 years - I tend to listen to most the things he says......

Tech jk

• 102 Answers
• Posted on May 08, 2009

SOURCE: on a 2006 chevy impala it tells you to tighten the gas cap

There is no sensor for a loose gas cap. What is happening is that the evaporative emission system is sensing a "Large Leak". Usually code p0455. The computer sees this as the most probable cause is a loose gas cap depending on several factors it looks at. You would need to clear the code(s) and see if that was the problem. If the light comes back on, then you have a problem in the system that will not let it seal. Possible solenoid problem, leaking hose / line, etc.

SOURCE: P0455 Tighten gas cap, engine light

i had same problem purchase new gas cap only ten bucks at wal mart. If still have problem e vac leak

SOURCE: I am getting a tighten gas cap message, however

The gas cap is most likely faulty. The gas cap is an integral part of the evaporative emission system. If it is not sealing or venting properly, it can affect the proper operation of this system. I would replace the gas cap and have the check engine light reset at an autoparts store. Most stores will scan/reset computer for free. Hope this helped and best wishes.