On my 2003 dodge caravan the check engine light is on. Took it to a machanic and he replaced the gas cap. 4 days later it came on again. He then replace the o-ring around the gas cap and checked all the emissions hoses. The code says its a emmissions leake. Machanic still cant figure it out. Can anyone help

Did you by any chance get gas before this happened? If you overfill your gas tank sometimes it affects the engine but when the gas goes down some in the tank everything normallizes

99% of the time, the gas cap wasn't tightened properly, or is leaking. Make sure you twist it tight and it clicks a few times. If the "Check Engine" light stays on after a few days, buy a new gas cap. Again it may take a few days to clear.

may have cracked vacuum lines.

If you are having no problems with the vehicle,then get a piece of tape and put over the light.Then you won't see the light on.

A loose or worn out gas cap can cause the check engine light to activate too.
Don't panic, it sometimes takes several days for the light to shut off, just make sure the cap is tight.

If you have an Advance Auto Parts store where ever you are, they will read the code and tell you exactly what to code is and what it means. Any mechanic who "guesses" isn't a mechanic at all - he's a thief. Emissions leak can be any number of things, but not the gas cap!

i would start with the gas cap and have them read the
code again. its a cheaper way to go first

Your problem is in the evaporative emission system which is designed to prevent the escape of fuel vapors from the fuel system. Leaks in the system, even small ones, can allow fuel vapors to escape into the atmosphere. The light coming on can be caused by one of the following:

1. Defective or loose fuel cap
2. EVAP canister or hose cracked- not connected
3. Purge or vent solenoid defective
4. Vacuum leak at engine Government regulations require on-board testing to make sure that the evaporative (EVAP) system is functioning properly. The leak detection system tests for EVAP system leaks and blockage. It also performs self-diagnostics. You have tried the easy fix, the gas cap. Finding the leak now will require special equipment and testing procedures, might be better left to a professional.

Please let me know if this information is helpful. Positive feedback is appreciated. Thank You!

Yah code 1684, it just tells you that battery/computer has been disconnected within last 50 starts. If it doesn't drive you nuts, give it some time, you'll be suprised how quick 50 starts will go by & light should go out

P0456 = EVAP Emissions Control System Leak Very Small

Is the gas cap on tight or is the seal damaged? If it needs replacement, get it from the dealer.