Tip & How-To about Dodge Ram 1500

Fix your gas cap so the check engine light stops coming on for $1

If you own a newer car and your check engine light is on because of a slow leak in the EVAP circut, and you want to try a quick fix before you buy a new gas cap, try taking the cap off (while the engine is off, otherwise it will set the check engine light on again) and put some vaseline around the rubber seal that contacts the filler neck. After some time, the rubber loses its flexibility and wont conform to the surface as well and the vaseline helps it to soften a little and seal up the minute air leaks

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why check engine light and code P0540 Large Evap Leak


did you reset codes after every repair ? is it a newer car ? there is a sensor in canister called a netural pressure vapor sensor they tend to leak or stick .causing evap codes , I chased the same code ,it would go out for about a week then come back in my case it was the new gas cap it was the wrong one for my car. it keeped building pressure in gas tank . and could hear it hissss when I would open it fuel up .

Aug 28, 2014 | Cars & Trucks

1 Answer

When i make a complete stop the cart takes a while to accelerate?


Millions of cars have that issue

The Evap System, will most easily be diagnosed &
your Gross Leak resolved,if you have a repair shop
with an EVAP Smoke Machine put on that system

The Gas Cap would be a PO442 (small leak) The way you
remember is, from the Hurst Olds 442, from the 1960's

The smoke test will blow some out the place of the leak,
like a rotted hose or broken evap valve.


Slow Acceleration---you work on after all check light issues
are resolved such as the evap leak.

Jun 02, 2012 | 2004 Nissan Murano

1 Answer

I have 2000 Montana. Service Eng light on, a check says: P0440 -- evaporated emission cntrl system small leak/low flow condition. Explanation: defective or loose fuel cap, evvap canister or hose cracked- not connected; purge or vent solenoid defective; vacuum leak at engine. My gas cap wont come off and I hear air at drv side rent, where cable runs female throttle body to an electrical component. What is my prob and how do I correct it?


P0440 small evap leak, If it was purge at fault the PCM would give you a purge failure code, If it was that vacuum leak you are hearing you would of have lean bank code, anything with the evap in the engine compartment is purge,the back where the fuel tank is or the canister is evap. so you have evap problem,slow leak a broken hose would be gross leak detected. as for electrical it would be solenoid evap.fix the gas cap. 3_17_2012_9_11_41_pm.jpg

Mar 17, 2012 | 2000 Pontiac Montana

1 Answer

I have a pontiac g6 that i just bought its a 2007 and it told me earlier to check my gas cap which i did then my check engine light came on and wont come off we went to auto zone and the machine said that it had a large evap leak but i dont know how to fix it or what a large evap leake is please help!!


An Evap leak in a car is usually fuel fumes leaking from the evap system. The purpose of the system is to expel pressure built in the gas tank, collect the fumes, and then at the right moment, purge the fumes into the intake to be burned. On newer cars, a leak in the system will set off the check engine light. The leak doesn't have to be big... in fact, it can be tiny. As in, can't see with the naked eye, tiny. A smoke machine is usually used to find the leak. A popular cause of an evap code is a loose gas cap, as the gas tank and filler neck itself are part of the system.

Aug 26, 2010 | 2008 Pontiac G6 Sedan

2 Answers

1998 Cheverolet Lumina, ''service engine soon'' and hard gear shift


I doubt the two problems are connected. I would try a new gas cap and see what happens since it runs fine. The service engine soon light won't reset on it's own right away.

Jan 11, 2010 | 1998 Chevrolet Lumina

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